22C - System Administrator - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
int n, m, v, p, q;
int main(){
   	cin >> n >> m >> v;
    if (v == 1) p = 2;
    else p = 1;
    if (m < n - 1 || m > n - 1 + (n - 2) * (n - 3) / 2) {
        cout << -1;return 0;
    }
    for (int i = 1; i <= n; i++){
        if (i == v) continue;
        cout << v << ' ' << i << endl;
    }
    m -= (n - 1);
    for (int i = 1; i <= n; i++){
        if (i == v || i == p) continue;
        for (int j = i + 1; j <= n; j++){
            if (j == v || j == p) continue;
            if (m == 0) return 0;
            cout << i << ' ' << j << endl;
            m--;
        }
    }
    return 0;
}