# https://school.programmers.co.kr/learn/courses/30/lessons/120912
# programmer, level0: 7의 개수, python3
def solution(array: list) -> int:
return sum([str(x).count('7') for x in array])
if __name__ == '__main__':
print(solution([7, 77, 17])) # 4
print(solution([10, 29])) # 0