#include <stdio.h>

int gcd(int x, int y) {
	if(y == 0) { return x; }
	return gcd(y, x % y);
}

int main() {
	int n, d;
	scanf("%d%d", &n, &d);
	
	
	printf("%d\n", n / gcd(n, d) - 1 );
	
	return 0;
}