Graph with vectors

#include <bits/stdc++.h>

using namespace std;

const int N = 1003;

int n, m;
vector <int> g[N];

int main(){
    cin >> n >> m;

    for (int i = 1; i <= m; i++) {
        int u, v;
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }

    for (int i = 1; i <= n; i++) {
        cout << "v-> " << i << " : ";
        for (int friends : g[i]) {
            cout << friends << " ";
        }
        cout << endl;
    }
}