#include <bits/stdc++.h>
using namespace std;

int main() {
  long long A;
  cin>>A;
  long long minNM=1000000000000000000;
  for(long long i=2;i<=50;i++){
    for(long long j=1;j<=64;j++){
      if(pow(i,j)>=A){
        minNM=min(minNM,i*j);
        break;
      }
    }
  }
  cout<<minNM<<endl;
  return 0;
}