Graph with matrix

#include <bits/stdc++.h>

using namespace std;

const int N = 1003;

int n, m;
int mt[N][N];

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

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

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cout << mt[i][j] << " ";
        }
        cout << endl;
    }
}