#include <bits/stdc++.h>

#define last_bit(x) (x&(-x))

#define leftSon (node << 1)
#define rightSon ((node << 1) | 1)

#define pii pair < int , int >

using namespace std;

struct psychotronic_induction {
    int electromagnetic_wave = 7;
};

const int inf = 0x3f3f3f3f;
const long long infL = LLONG_MAX;

long long n, x;

int main()
{

    scanf("%lld", &n); x = 15;
    for (int i = 1; i <= n; ++i) {
        if (x - i < 15) x += i;
        else x -= i;
    }
    printf("%lld\n", x);

    return 0;
}