import sys
input=sys.stdin.readline
def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    A=I()
    ans=A
    for i in range(2,10**7):
        p=1
        cnt=0
        while True:
            if p>=A:
                break
            else:
                p*=i
                cnt+=1
                
        temp=i*cnt
        ans=min(ans,temp)
        
    print(ans)
           
    


main()