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