#include <bits/stdc++.h>

using namespace std;

int main(){

int t;

scanf("%d", &t);

vector<int>a,b;

for(int i=0; i<t; i++){

    int n;

    scanf("%d", &n);

    for(int j=0; j<n; j++){

        int c,d;

        scanf("%d %d", &c, &d);

        a.push_back(c), b.push_back(d);

    }

    while(1){

        int ok=0;

        for (int k=0; k<n-1; k++){

        if(a[k]>a[k+1]){

                swap(a[k], a[k+1]);

                swap(b[k], b[k+1]);

                ok=1;}

        else if(a[k]==a[k+1]){

            if(b[k]<b[k+1]){

                    swap (a[k], a[k+1]);

                    swap (b[k], b[k+1]);

                    ok=1;}

        }

    }

    if(ok==0)break;

    }

        for(int m=0; m<n; m++){

        printf("%d %d\n", a[m], b[m]);

    }

    a.clear(), b.clear();

}


return 0;


}