#include<vector>
#include<fstream>

using namespace std;

#define MAX_N 100000


int N, M;
vector<int> grafo[MAX_N];
bool mess[MAX_N];
int turing[MAX_N];
int navi[MAX_N];

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


int main(int argc, char **argv){

  ifstream in("input.txt");
  in >> N >> M;
  for(int i=0;i<N;i++){
    int m,s;
    in >> m >> s;
    grafo[m].push_back(s);
    turing[m] = s;
  }
  for(int i=0;i<M-N;i++){
    int m,s;
    in >> m >> s;
    grafo[m].push_back(s);
  }
  in.close();

  ofstream out("output.txt");
  if(dfs(0,0)){
    for(int i=0;i<N;i++){
      out << i <<" "<<navi[i] << "\n";
    }
  }else{
    out<<"-1\n";
  }
  
  out.close();
  return 0;
}