#include <iostream>
int multiply(int x, int y) {
if (y > 0) {
return (x + multiply(x, y - 1));
}
if (y < 0) {
return -multiply(x, -y);
}
return 0;
}
int main()
{
std::cout << multiply(3, 7) << "\n";
std::cout << multiply(4, 16) << "\n";
std::cout << multiply(5, 0) << "\n";
std::cout << multiply(0, 8) << "\n";
std::cout << multiply(2, -5) << "\n";
std::cout << multiply(-4, 6) << "\n";
std::cout << multiply(-5, -7) << "\n";
}
/*
run:
21
64
0
0
-10
-24
35
*/