#include <stdio.h>
int mystery(int a, int b); // function prototype

int main(void) {
	printf("%s", "Enter two positive integers: ");
	int x = 0; // first integer
	int y = 0; // second integer
	scanf("%d%d", &x, &y);
	printf("The result is %d\n", mystery(x, y));
}

// Parameter b must be a positive integer
// to prevent infinite recursion
int mystery(int a, int b) {
// base case
	if (1 == b) {
		return a;
	} else if (b > 1) { // recursive step
		return a + mystery(a, b - 1);
	} else {
		return -a + mystery(a, b + 1);
	}
}