import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sn = new Scanner(System.in);

    int n = sn.nextInt();
    int m = sn.nextInt();
    
    int cnt = 0;
    
    if (n > 1) {
      for (int i = 1; i < n; i ++) {
        cnt = cnt + (n - i);
      }
    }
    
    if (m > 1) {
      for (int i = 1; i < m; i ++) {
        cnt = cnt + (m - i);
      }
    }
    
    System.out.print(cnt);
  }
}
/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