Choose Your Own Adventure!

    1#include <bits/stdc++.h>
    2using namespace std;
    3using ll = long long;
    4using i128 = __int128;
    5const int inf = 1e9;
    6const ll INF = 1e18; //❄️
    7int main() {
    8    ios::sync_with_stdio(0); cin.tie(0); 
    9    int n, m; cin >> n >> m;
    10    if (m > n + 1) {
    11        cout << -1 << '\n';
    12        return 0;
    13    }
    14    const int mod = n + m + 1;
    15    int x = 1;
    16    for (int i = 0; i < n; i++) {
    17        int a = ++x, b = ++x;
    18        a %= mod; b %= mod;
    19        if (a == 0) a += 2;
    20        if (a == 1) a++;
    21        if (b == 0) b += 3;
    22        if (b == 1) b++;
    23        if (a == b) a++;
    24        if (a == i + 1) a++;
    25        if (b == i + 1) b++;
    26        cout << a << " " << b << '\n';
    27    }
    28    return 0;
    29}