// C++ code to demonstrate the working of lower_bound()
#include <bits/stdc++.h>
using namespace std;
 
// Driver's code
int main()
{
	pair<int, int> v[10];
	for(int i=0;i<10;i++){
		v[i] = (make_pair(i,i));
	}
	for(int i=0;i<10;i++){
		cout<<v[i].first<<" "<<v[i].second<<endl;
	}
 
	int index = lower_bound(v, v+10, make_pair(21,21), 
	[](const pair<int,int>& lhs, const pair<int,int>& rhs){ return lhs.first < rhs.first; }) - v;
 
	cout<<index<<endl;
}
 

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