mod = 1000000007
eps = 10**-9


def main():
    import sys
    input = sys.stdin.readline

    A = int(input())
    ans = 10**20
    for d in range(2, 100):
        for b in range(100):
            if d ** b >= A:
                ans = min(ans, d*b)
    print(ans)


if __name__ == '__main__':
    main()