#include <bits/stdc++.h>

#include <atcoder/all>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
using namespace std;
using namespace atcoder;

typedef long long ll;

// n番目の素数
int f(int n) {
    if (n == 1) return 2;
    if (n == 2) return 3;
    int cnt = 2;
    for (int i = 5;; i += 2) {
        bool ok = true;
        for (int j = 3; j * j <= i; j += 2) {
            if (i % j == 0) {
                ok = false;
                break;
            }
        }
        if (ok) {
            cnt++;
            if (cnt == n) return i;
        }
    }
    return -1;
}

int main() {
    int n;
    cin >> n;
    cout << f(n) << endl;
}