import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int M = sc.nextInt();
        int a = 0;
        if(N > 1 && M > 1){
            for(int i = 1; i < N; i++){
                for(int j = i; j < N; j++){
                    a++;
                }
            }
            for(int i = 1; i < M; i++){
                for(int j = i; j < M; j++){
                    a++;
                }
            }
        }else if(N > 1 && M <= 1){
            for(int i = 1; i < N; i++){
                for(int j = i; j < N; j++){
                    a++;
                }
            }
        }else if(M > 1 && N <= 1){
            for(int i = 1; i < M; i++){
                for(int j = i; j < M; j++){
                    a++;
                }
            }
        }else{
            a = 0;
        }
        System.out.println(a);
    }
}
/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