diff --git a/python_exercise_sol/solution1.py b/python_exercise_sol/solution1.py
new file mode 100644
index 0000000..72a7417
--- /dev/null
+++ b/python_exercise_sol/solution1.py
@@ -0,0 +1,17 @@
+# String's Vowel and Consonent Counter 
+
+def counter(str):
+    vow="aeiou"
+    vow_count=0
+    conso_count=0
+    for char in str.lower().strip():
+        if char in vow:
+            vow_count+=1
+        else:
+            conso_count+=1
+
+    return vow_count,conso_count
+
+str=input("Enter your valid string: ")
+v,c=counter(str)
+print(f"Vowel count is : {v}\nConsonent count is :{c}")
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diff --git a/python_exercise_sol/solution2.py/run_test.py b/python_exercise_sol/solution2.py/run_test.py
new file mode 100644
index 0000000..5aa25fa
--- /dev/null
+++ b/python_exercise_sol/solution2.py/run_test.py
@@ -0,0 +1,17 @@
+from datetime import datetime, timedelta
+from time_window import TimeWindow
+
+start = datetime(2024, 1, 1, 0, 0)
+final = datetime(2024, 1, 1, 6, 0)
+delta = timedelta(hours=1)
+
+tw = TimeWindow(start, final, delta)
+print(tw)
+for m, ws, we in zip(tw.model_times, tw.window_starts, tw.window_ends):
+    print(f"model={m}  window=({ws} -> {we})")
+
+print("\nNow trying the bug: a negative delta...")
+try:
+    bad = TimeWindow(start, final, timedelta(hours=-1))
+except ValueError as e:
+    print(f"Caught expected error: {e}")
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diff --git a/python_exercise_sol/solution2.py/time_window.py b/python_exercise_sol/solution2.py/time_window.py
new file mode 100644
index 0000000..fb5f50d
--- /dev/null
+++ b/python_exercise_sol/solution2.py/time_window.py
@@ -0,0 +1,107 @@
+from datetime import datetime, timedelta
+
+
+class TimeWindow:
+    """
+    Calculates the hour-long model stop times ("model times") between a
+    start and final time, and the +/- 30 minute observation window
+    ("window times") around each model stop.
+
+    Parameters
+    ----------
+    start_time : datetime
+        Time of the first experiment.
+    final_time : datetime
+        Time of the last experiment. Must be after start_time.
+    delta : timedelta
+        Duration between experiments (e.g. timedelta(hours=1)).
+        Must be a positive, non-zero duration.
+    window_halfwidth : timedelta, optional
+        Half-width of the observation window around each model stop.
+        Defaults to timedelta(minutes=30).
+    """
+
+    def __init__(self, start_time, final_time, delta,
+                 window_halfwidth=timedelta(minutes=30)):
+
+        # --- Type checks -------------------------------------------------
+        if not isinstance(start_time, datetime):
+            raise TypeError("start_time must be a datetime object")
+        if not isinstance(final_time, datetime):
+            raise TypeError("final_time must be a datetime object")
+        if not isinstance(delta, timedelta):
+            raise TypeError("delta must be a timedelta object")
+        if not isinstance(window_halfwidth, timedelta):
+            raise TypeError("window_halfwidth must be a timedelta object")
+
+        # --- Value checks (this is where the bug lived) -------------------
+        # delta must be strictly positive, otherwise the number of
+        # experiments still "counts" fine (abs value / floor division can
+        # look reasonable) but every window/model time after the first is
+        # computed by walking *backwards* instead of forwards.
+        if delta <= timedelta(0):
+            raise ValueError(
+                f"delta must be a positive, non-zero timedelta, got {delta}"
+            )
+
+        # final_time must actually be after start_time, or we again get
+        # a nonsensical (or negative) number of experiments.
+        if final_time <= start_time:
+            raise ValueError(
+                "final_time must be after start_time "
+                f"(got start_time={start_time}, final_time={final_time})"
+            )
+
+        # delta should not be longer than the total experiment period,
+        # otherwise there are zero experiments, which is probably not
+        # what the user intended.
+        total_duration = final_time - start_time
+        if delta > total_duration:
+            raise ValueError(
+                f"delta ({delta}) is larger than the total time between "
+                f"start_time and final_time ({total_duration})"
+            )
+
+        # window_halfwidth must be positive too, and — since the model
+        # is stopped every `delta` — it probably shouldn't be larger
+        # than half of delta, or windows would overlap.
+        if window_halfwidth <= timedelta(0):
+            raise ValueError(
+                "window_halfwidth must be a positive, non-zero timedelta, "
+                f"got {window_halfwidth}"
+            )
+        if window_halfwidth * 2 > delta:
+            raise ValueError(
+                f"window_halfwidth ({window_halfwidth}) is too large for "
+                f"delta ({delta}); observation windows would overlap"
+            )
+
+        self.start_time = start_time
+        self.final_time = final_time
+        self.delta = delta
+        self.window_halfwidth = window_halfwidth
+
+        # Number of hour-long experiments between start and final time.
+        self.n_experiments = int(total_duration / delta)
+
+        self._compute_times()
+
+    def _compute_times(self):
+        """Compute the list of model stop times and their windows."""
+        self.model_times = [
+            self.start_time + i * self.delta
+            for i in range(self.n_experiments + 1)
+        ]
+        self.window_starts = [
+            t - self.window_halfwidth for t in self.model_times
+        ]
+        self.window_ends = [
+            t + self.window_halfwidth for t in self.model_times
+        ]
+
+    def __repr__(self):
+        return (
+            f"TimeWindow(start_time={self.start_time!r}, "
+            f"final_time={self.final_time!r}, delta={self.delta!r}, "
+            f"n_experiments={self.n_experiments})"
+        )
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