1879A - Rigged - CodeForces Solution

#include <bits/stdc++.h>
#define ll long long
using namespace std;

int main(){

ll t;
cin>>t;

while(t--){

    ll n;
    cin>>n;

    ll cmp1, cmp2;
    cin>>cmp1>>cmp2;
    
    bool possible= true;
    for(ll i= 1; i<n; i++){
        
        ll u1, u2;
        cin>>u1>>u2;
        
        if(u1>=cmp1 && cmp2 <= u2){
            possible= false;
        }
    }
    
    if(possible){
        cout<<cmp1<<endl;
    }
    
    else{
        cout<<-1<<endl;
    }
}

return 0;
}