Unexpected value of a shared pointer [duplicate]

I have recently started learning shared pointers and need some help.

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

class A
{
    public:
    int a;
    A (int x) {
      a = x;
    }
    int print() {
        return a;
    }
};

int main()
{   
    shared_ptr<vector<shared_ptr<A>>> vec1 = make_shared<vector<shared_ptr<A>>>(1);
    (*vec1)[0] = make_shared<A>(50);
    shared_ptr<vector<shared_ptr<A>>> vec2 = make_shared<vector<shared_ptr<A>>>();
    vec2->push_back((*vec1)[0]);
    for (shared_ptr<A>& obj : *vec2) {
        obj = make_shared<A>(100);
    }
    cout << (*((*vec1)[0])).a;
    return 0;
}

This gives the output as 50 while I expected it to be 100. Can some please explain why? And what can I do to get this as 100? TIA!