public int combination(int n, int k) {
		double numer = 1.0;
		double denom = 1.0;
		int start;
		int end;
		if(k > n/2){
			start = k+1;
			end = n-k;
		}else{
			start = n-k+1;
			end = k;
		}
		for (int i=start; i<=n; i++) numer *= i;
		for (int i=1; i<=end; i++) denom *= i;
		return (int) (numer/denom);
		
	}