regex module

import re

def main():
    f = open('text.txt', 'r')
    for eachLine in f:
        if (len(eachLine)==10):
          f_num=re.search(r'^[789]',eachLine)
            if (f_num==9):
                print("YES")

        else : print("NO")

if __name__ == '__main__':
    main()