#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int N,M;
vector <pair<int,int>> v;
int main(){
cin>>N>>M;
int a=0,b=0;
int result = 0, l = -1, r = -1;
for(int i=0;i<M;i++) {
cin>>a>>b;v.push_back({a,b});}
sort(v.begin(),v.end());
for(int i=0;i<v.size()-1;i++){
if(r < v[i].first){
l = v[i].first;
r = v[i].second;
}
else r = max(r, v[i].second);
cout<<l<<" "<<r;
}
}
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