#include <iostream>
#include <string>
#include <sstream>

struct A
{
    std::string text;
};

std::istream& operator>>(std::istream& is, A& a)
{
    return is >> a.text;
}

int f(std::string const &s)
{
    A a;
    int b;
    if (std::istringstream{ s } >> a >> b)
    {
        return std::stoi(a.text) + b;
    }
    return 0;
}

int main()
{
    std::cout << f("1 2") << std::endl;
}