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

bool isp(int n) {
  if (n < 2) return false;
  else if (n == 2) return true;
  else if (n % 2 == 0) return false;
  for (int i = 3; i <= (int)sqrt(n); i += 2) if (n % i == 0) return false;
  return true;
}

int main() {
  int N;
  cin >> N;
  if (N == 1) return cout << 1 << "\n", 0;
  for (int i = 100001, cnt = 1; ; i++) {
    if (isp(i)) continue;
    cnt++;
    if (cnt == N) return cout << i << "\n", 0;
  }
}