error while using pop_back in vector code example

Example 1: vector pop back

// vector::pop_back
#include <iostream>
#include <vector>

int main ()
{
  std::vector<int> myvector;
  int sum (0);
  myvector.push_back (100);
  myvector.push_back (200);
  myvector.push_back (300);

  while (!myvector.empty())
  {
    sum+=myvector.back();
    myvector.pop_back();
  }

  std::cout << "The elements of myvector add up to " << sum << '\n';

  return 0;
}

Example 2: c++ vector pop_back

#include <bits/stdc++.h> 
using namespace std;
int main(){
    vector<int> v1{10, 20, 30, 40, 50};
    
    //removing elemenets
    v1.pop_back();  //removes 50
    v1.pop_back();  //removes 40

}