heap in cpp stl

// C++ code to demonstrate the working of  
// push_heap() and pop_heap() 
#include<bits/stdc++.h>  
using namespace std; 
int main() 
{ 
      
    // Initializing a vector 
    vector<int> v1 = {20, 30, 40, 25, 15}; 
      
    // Converting vector into a heap 
    // using make_heap() 
    make_heap(v1.begin(), v1.end()); 
      
    // Displaying the maximum element of heap 
    // using front() 
    cout << "The maximum element of heap is : "; 
    cout << v1.front() << endl; 
      
    // using push_back() to enter element 
    // in vector 
    v1.push_back(50); 
      
    // using push_heap() to reorder elements 
    push_heap(v1.begin(), v1.end()); 
      
    // Displaying the maximum element of heap 
    // using front() 
    cout << "The maximum element of heap after push is : "; 
    cout << v1.front() << endl; 
      
     // using pop_heap() to delete maximum element 
    pop_heap(v1.begin(), v1.end()); 
    v1.pop_back(); 
      
    // Displaying the maximum element of heap 
    // using front() 
    cout << "The maximum element of heap after pop is : "; 
    cout << v1.front() << endl; 
      
    return 0; 
}