#include<iostream>
using namespace std;
int factorial(int a);
int Pascal(int row, int col);
void main(){
int row = 0, col = 0;
do{
cin>>row;
cin>>col;
if(Pascal(row,col) == -1){
cout<<" . ."<<endl;
}
else{
cout<<" 각 "<<row<<" "<<col<<" "<<Pascal(row,col)<<"."<<endl;
};
}while(Pascal(row,col) == -1);
}
int factorial(int a){
int output= 1;
if( a == 0 ){
return output;
}
else{
for( ; a> 0 ; a--){
output *= a;
}
return output;
}
}
int Pascal(int row, int col){
if(row == col || col == 1){
return 1;
}
else if( row < col ){
return -1;
}
else{
return factorial(row-1) / ( factorial(col-1) * factorial(row - col) );
}
}