/************************************************
*                                               *
*     La battaglia del convoglio      VR370108  *
*                                               *
************************************************/

#include <cstdio>
#include <cassert>
#include <vector>
#include <algorithm>

#define maxN 100000
#define maxM 200000

using namespace std;

vector <int> graph[maxN];

int t[maxN];
bool msg [maxN];
int navi [maxN];
int N, M;

bool dfs(int x, int y);

int main(){
    
    FILE* in;
    in = fopen("input.txt", "r");
    assert(in);

    fscanf(in, "%d %d", &N, &M);


    for(int i = 0; i < N; i++){
        int m, n;
        fscanf(in, "%d %d", &m, &n);
        graph[m].push_back(n);
        t[m] = n;
    }


    for(int i = 0; i < M-N; i++){
        int o, p;
        fscanf(in, "%d %d", &o, &p);
        graph[o].push_back(p);
    }
    fclose(in);
        
    FILE* output;
    output = fopen("output.txt", "w");
    

    if(dfs(0,0)){
        int m, n;
        for(int i = 0; i < N; i++){
            m = i;
            n = navi[m];
            fprintf(output, "%d %d\n", m, n);
        }    
    } else {
        fprintf(output, "-1\n");
    }
    fclose(output);
    
    return 0;
}

bool dfs(int x, int y){
    if(y == N){
        return false;
    }
    if(x == N){
        return true;
    }

    for(vector<int>::iterator i = graph[x].begin(); i!= graph[x].end(); i++){  
        if(!msg[*i]){
            msg[*i] = true; 
            navi[x] = *i;
            if(t[x] == *i){
                y++;
            }
            if(dfs(x+1, y)){
                return true;
            } else {
                msg[*i] = false;
                navi[x] = -1;
            }
       }
       if(i == graph[x].end()){
            return false; 
       }
    }
}