c++ - How to access pair elements nested inside pair in a vector in stl -

i have vector :

vector < pair < int, pair < int,int > > > v 

i want access 3 elements . how can through iterator? have declared iterator it1 , it2 below :

#include <bits/stdc++.h> using namespace std; int main()  {  int t; scanf("%d",&t); while(t--) {     vector<pair<int,pair<int,int> > > v;     int n,a,b,i;     scanf("%d",&n);     for(i=0;i<n;i++)     {         scanf("%d%d",&a,&b);         v.push_back(make_pair(b,make_pair(a,i+1)));     }     sort(v.begin(),v.end());     vector<pair<int,pair<int,int> > > :: iterator it1=v.begin();     vector<pair<int,pair<int,int> > > :: iterator it2=v.begin()+1;     printf("%d ",(it1->first)->second);          while(it2!=v.end())         {             if(it2->first.first>it1.first)             {                 printf("%d ",it2.first.second);                 it1=it2;              }             it2++;         }      }     return 0; } 

follow types.

if it iterator on

vector<pair<int, pair<int, int>>>  

then *it

pair<int, pair<int, int>>   

so it->first (a.k.a. (*it).first) int, , it->second pair<int,int>.

this means elements are

it->first it->second.first it->second.second