#include <iostream>
#include <vector>
using namespace std;

int main(){
	int n,m;
	while(cin >> n >> m && n || m){
		vector<int> data(n);
		vector<int> del;
		int i=1;
		for(int i=0;i<n;i++){
			data[i] = i+1;
		}
		for(	vector<int>::iterator it = data.begin();
			data.size()!=1;
		){
			if(it == data.end()){
				it = data.begin();
			}
			if(i%m==0){
				it = data.erase( it );
			}else{
				it++;
			}
			i++;
		}
		cout << data[0] << endl;
	}
}