Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        amari = [7]
        ans = 1
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                seven = seven*10+7

                if seven in amari:
                    print(-1)
                    break
                ans += 1
                amari.append(seven)


if __name__ == '__main__':
    main()


Fixed submission:
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        amari = set([7])
        ans = 1
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                seven = seven*10+7
                if seven in amari:
                    print(-1)
                    break
                ans += 1
                amari.add(seven)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        ans = 1
        pre = INF
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                if pre==seven:
                    print(-1)
                    break
                pre = seven
                seven = seven*10+7
                ans += 1


if __name__ == '__main__':
    main()


Fixed submission:
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        amari = set([7])
        ans = 1
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                seven = seven*10+7
                if seven in amari:
                    print(-1)
                    break
                ans += 1
                amari.add(seven)


if __name__ == '__main__':
    main()

Buggy python submission (verdict: Time Limit Exceeded):
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        ans = 1
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                seven = seven*10+7
                ans += 1


if __name__ == '__main__':
    main()


Fixed submission:
import sys
read = sys.stdin.read
readline = sys.stdin.buffer.readline

sys.setrecursionlimit(10 ** 8)
INF = float('inf')
MOD = 10 ** 9 + 7


def main():
    K = int(readline())
    if K%2==0:
        print(-1)
    else:
        seven = 7
        amari = set([7])
        ans = 1
        while True:
            seven = seven%K
            if seven==0:
                print(ans)
                break
            else:
                seven = seven*10+7
                if seven in amari:
                    print(-1)
                    break
                ans += 1
                amari.add(seven)


if __name__ == '__main__':
    main()