
void main()
{
	int n, m;
	int i, j, m1, cur, t;
	int next[10000];
	int b=0;
	while (1)
	{
		scanf("%d %d", &n, &m);
		if (n==0 && m==0)
			break;
		//??????????????
		for (i=1;i<=n;i++)
			next[i]=i+1;
		next[n]=1;
		//?????????cur
		cur=1;
		//?n-1??????????cur==next[cur]???????????
		for (i=1;i<=n-1;i++)
		{
			//???????
			m1=m%(n-i+1);
			if (m1==0) m1=n-i+1;
			else if (m1==1) m1=n-i+1+1;
			//??
			for (j=0;j<m1-2;j++)
				cur=next[cur];
			//??cur???????
			t=next[next[cur]];
			next[next[cur]]=0;
			next[cur]=t;
			//?????????1??
			cur=next[cur];
		}
		if (b) printf("\n");
		printf("%d", cur);
		b=1;
	}
}