EATTWICE-EDITORIAL

simply and easy way

#include<iostream>
#include<bits/stdc++.h>
#define int long long

using namespace std;

main() {
int test;
cin>>test;
while(test--){
    int n=0,m=0;
    cin>>n>>m;
    int a[m+1];
      for(int i=0;i<m+1;i++)
       {
           a[i]=0;
       }
    int temp=0,temp2=0;
    for(int i=0;i<n;i++)
    {
        cin>>temp>>temp2;
        if(a[temp]<temp2)
        {
            a[temp]=temp2;
        }
        
    }
    
   sort(a+1,a+m+1);
  
    cout<<a[m]+a[m-1]<<endl;
}
return 0;
}