#include <bits/stdc++.h>

using namespace std;

int count(int N) {
  int v = sqrt(N);
  vector<int> sc(v + 1), lc(v + 1);
  for (int i = 1; i <= v; ++i) sc[i] = i - 1;
  for (int i = 1; i <= v; ++i) lc[i] = N / i - 1;
  for (int p = 2; p <= v; ++p) if (sc[p] != sc[p - 1]) {
    int c = sc[p - 1];
    int q = p * p;
    int w = v / p;
    for (int i = 1; i <= w; ++i) lc[i] -= lc[i * p] - c;
    int e = min(v, N / q);
    int m = N / p;
    for (int i = w + 1; i <= e; ++i) lc[i] -= sc[m / i] - c;
    for (int i = v; i >= q; --i) sc[i] -= sc[i / p] - c;
  }

  int ret = sc[int(cbrt(N))];
  for (int p = 2; p <= v; ++p) if (sc[p] != sc[p - 1]) {
    ret += lc[p] - sc[p];
  }
  return ret;
}

void solve() {
   int N; scanf("%d", &N);
   int i = 1; while (count(i) < N) i <<= 1;
   int ans = 0;
   for (; i > 0; i >>= 1) if (count(ans + i) < N) ans += i;
   printf("%d\n", ans + 1);
}

int main() {
  solve();
  return 0;
}