What will be the output of the following C++ code?

#include <iostream>
#include <vector>
using namespace std;
int main ()
{
    vector<int> a (3, 0);
    vector<int> b (5, 0);
    b = a;
    a = vector<int>();
    cout << "Size of a " << int(a.size()) << '\n';
    cout << "Size of b " << int(b.size()) << '\n';
    return 0;
}