#include <iostream>
#include <math.h>

using namespace std;


void dfs(int **matr, int *viewed, int v, int n, int **matrN) {
    viewed[v] = 1;

    for (int i = 0; i < n; ++i) {
        if (matr[v][i] and !viewed[i]) {
            matrN[v][i] = 1;
            dfs(matr, viewed, i, n, matrN);
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;
    int **matr = new int *[n];
    for (int i = 0; i < n; ++i) {
        matr[i] = new int[n];
    }

    int **matrN = new int *[n];
    for (int i = 0; i < n; ++i) {
        matrN[i] = new int[n];
    }
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            matrN[i][j] = 0;
        }
    }

    int *viewed = new int[n];
    for (int i = 0; i < n; ++i) {
        viewed[i] = 0;
    }


    int I, J;
    for (int i = 0; i < m; ++i) {
        cin >> I >> J;
        matr[I - 1][J - 1] = 1;
    }

    dfs(matr, viewed, 0, n, matrN);

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            if (matrN[i][j]) {
                cout << min(i, j) + 1 << " " << max(i, j) + 1 << endl;
            }
        }
    }
}