import java.util.*;

class Main {
        public static void main(String args[]) {
                try (Scanner sc = new Scanner(System.in)) {
                        long N = sc.nextLong(), D = sc.nextLong();
                        System.out.println(N / gcd(N, D) - 1);
                }
        }
        private static long gcd(long A, long B) {
                if (A < B) {
                        return gcd(B, A);
                }
                if (B == 0) {
                        return A;
                }
                return gcd(B, A%B);
        }
}