#include<cstdio>
#include<cmath>
using namespace std;
const int N=2e6+10; bool vis[N];
int main() {
  //freopen("jump.in","r",stdin);
  //freopen("jump.out","w",stdout);
  int n,d,idx=1,cnt=0; scanf("%d %d",&n,&d);
  while(true) {
  	vis[idx]=true,idx=(idx+d-1)%n+1;
  	if(vis[idx]) break;
  	cnt++;
  }
  printf("%d",cnt);
  return 0;
}