import java.util.*;

public class Main{
    public static void main(String args[]){
        Scanner scanner = new Scanner(System.in);
        int N = scanner.nextInt();
        int M = scanner.nextInt();

        int res = 0;
        if(N > 0) {
            res += N * (N-1) / 2;
        }
        if(M > 0){
            res += M * (M-1) / 2;
        }
        System.out.println(res);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz