#include "bits/stdc++.h"

using lint = int64_t;

using namespace std;

map<lint,lint> memo;

int countDiv(lint x) {
    set<lint> st;
    for(lint i = 1; i <= sqrt(x) + 1; i++) {
        if(x % i == 0) {
            st.insert(i);
            st.insert(x/i);
        }
    }
    return st.size();
}

lint f(lint x) {
    lint ans = 1;
    for(int i = 0; i < countDiv(x); i++) {
        ans *= x;
    }
    return ans;
}

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  lint n;
  cin >> n;
  lint ans = lint(1e18) + 1;
  for(int i = 2; i <= 70; i++) {
    lint raiz1 = pow(n, 1.0/i) - 1;
    lint raiz2 = pow(n, 1.0/i);
    lint raiz3 = pow(n, 1.0/i) + 1;

    if(f(raiz1) == n) {
        ans = min(raiz1, ans);
    }
    if(f(raiz2) == n) {
        ans = min(raiz2, ans);
    }
    if(f(raiz3) == n) {
        ans = min(raiz3, ans);
    }
  }

  if(ans != lint(1e18) + 1) {
    cout << ans << endl;
  } else cout << -1 << endl;
  
  return 0;
}