#include <bits/stdc++.h>
using namespace std;
bool isPrime(int a) {
  for (int i = 2; i * i <= a; i++) {
    if (a % i == 0) return false;
  }
  return true;
}
int reverse(int a) {
  int res = 0;
  while (a != 0) {
    res = res * 10 + a % 10;
    a /= 10;
  }
  return res;
}
int main() {
  int n;
  cin >> n;
  int count = 0;
  for (int i = 2;; i++) {
    if (isPrime(i)) {
      int t = reverse(i);
      if (isPrime(t) && t != i) {
        count++;
        if (n == count) {
          cout << i;
          return 0;
        }
      }
    }
  }
  return 0;
}

### Prompt

Your challenge is to write a CPP solution to the following problem:

qd ucyhf yi q fhycu dkcruh mxeiu huluhiu yi q tyvvuhudj fhycu dkcruh. oekh jqia yi je vydt jxu djx ucyhf.

Input

jxu ydfkj sediyiji ev q iydwbu ydjuwuh d (1 ≤ d ≤ 11184) — jxu edu-rqiut ydtun ev jxu ucyhf je vydt.

Output

ekjfkj q iydwbu dkcruh.

Examples

Input

1


Output

13

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
bool isPrime(int a) {
  for (int i = 2; i * i <= a; i++) {
    if (a % i == 0) return false;
  }
  return true;
}
int reverse(int a) {
  int res = 0;
  while (a != 0) {
    res = res * 10 + a % 10;
    a /= 10;
  }
  return res;
}
int main() {
  int n;
  cin >> n;
  int count = 0;
  for (int i = 2;; i++) {
    if (isPrime(i)) {
      int t = reverse(i);
      if (isPrime(t) && t != i) {
        count++;
        if (n == count) {
          cout << i;
          return 0;
        }
      }
    }
  }
  return 0;
}

```