#include <iostream>
#include "bits/stdc++.h";
using namespace std;
int main() {
// your code goes here
vector<vector<int>> arr = {{1,3},{1,2},{7,8},{8,10}};
sort(arr.begin(), arr.end());
for(auto i : arr){
cout<<i[0]<<" "<<i[1]<<endl;
}
return 0;
}
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