mod = 1000000007
eps = 10**-9


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

    A = int(input())
    ans = 10**20
    flg = 0
    for d in range(2, A+1):
        for b in range(100):
            if d ** b >= A:
                if ans >= d * b:
                    ans = d*b
                else:
                    flg = 1
                break
        if flg:
            break
    print(ans)


if __name__ == '__main__':
    main()