#include<stdio.h>

int gcd(int a,int b){
  int r=a%b;
  while(r>0){
    a=b;
    b=r;
    r=a%b;
  }
  return b;
}

void run(void){
  int n,d;
  scanf("%d%d",&n,&d);
  int g=gcd(n,d);
  printf("%d\n",n/g-1);
  return;
}

int main(void){
  run();
  return 0;
}