
int main(void)
{
	int m,n;
	int *p;
	int i,j,k,l;
	while(1){
	   scanf("%d%d",&n,&m);
	   if(n==0&&m==0)
		  break;

	      p=(int*)malloc(sizeof(int)*n);   /*??????????,???????????*/

	      for(i=0;i<n;i++){
		     p[i]=0;
		  }

	      k=n,j=1;
	
       	  for(i=0;i<n;i=(i+1)%n){          /*i=(i+1)%n ??????*/
		      if(p[i]){
			  continue;
			  }
		      
			  if(j++==m){
			    p[i]=1;
			    k--;
			    j=1;
			  }
		
		      if(k==0){
			    printf("%d\n",i+1);
			    break;
			  }
		  }
		 free(p);
	}
	return 0;
}