What do I do if this error happens?

[esthicodes]

~/pset1/mario/mario-less/ $ make mario
clang -ggdb3 -O0 -std=c11 -Wall -Werror -Wextra -Wno-sign-compare -Wno-unused-parameter -Wno-unused-variable -Wshadow mario.c -lcrypt -lcs50 -lm -o mario
/usr/bin/ld: /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/crt1.o: in function _start': (.text+0x24): undefined reference to main'
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [: mario] Error 1

Thank you