import sys
import re


def p(A):
    if A == '0':
        return True

    mo = re.match('^[123456789][0123456789]*?$', A)
    if not mo:
        return False

    i = int(A)
    return 1 <= i <= 12345


def _solve(A, B):
    return p(A) and p(B)


def solve(in_):
    A = next(in_).strip()
    B = next(in_).strip()
    return _solve(A, B)
    

def main():
    answer = solve(sys.stdin)
    print('OK' if answer else 'NG')


if __name__ == '__main__':
    main()