What will be printed by this program if you enter

What will be printed by this program if you enter 3 values from the console: 1, 2, and 3?

#include <iostream>
#include <string>
#include <map>

using namespace std;

int main() {
    string s;
    map<string, int> m;

    while (cin >> s) {
        m[s] = m.size();
    }

    for (map<string, int>::iterator i = m.begin(); i != m.end(); ++i) {
        cout << i->second << " ";
    }

    return 0;
}

Explanation

The C ++ standard does not specify the calculation order of the operands of the assignment operator, so the result may be different (depends on the compiler): "0 1 2" or "1 2 3". This is determined by what operation will be performed first: determining the size of the map or adding a new element to the map. The correct answer is "the result is not defined".