110A - Nearly Lucky Number
12345678910111213141516
def lucky_number(num):
count = 0
for i in num:
if i == '4' or i == '7':
count += 1
# print(count)
if count == 4 or count == 7:
return "YES"
else:
return "NO"
if __name__ == "__main__":
num = input()
print(lucky_number(num))
Python
INFO