import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    }
} Main public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    } main {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) String strArray[] = br.readLine().split(" "); strArray br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " int N = Integer.parseInt(strArray[0]); N Integer.parseInt(strArray[0]) Integer.parseInt Integer strArray[0] strArray 0 int M = Integer.parseInt(strArray[1]); M Integer.parseInt(strArray[1]) Integer.parseInt Integer strArray[1] strArray 1 int sum = 0; sum 0 for (int i = 1; i < N; i++) {
	    sum += i;
	} int i = 1; int i = 1; i 1 i < N i N i++ i++ i {
	    sum += i;
	} {
	    sum += i;
	} sum += i sum i for (int i = 1; i < M; i++) {
	    sum += i;
	} int i = 1; int i = 1; i 1 i < M i M i++ i++ i {
	    sum += i;
	} {
	    sum += i;
	} sum += i sum i System.out.println(sum) System.out.println System.out System System.out sum String args[] args public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    }
} public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    public static void main(String args[]) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	String strArray[] = br.readLine().split(" ");
	int N = Integer.parseInt(strArray[0]);
	int M = Integer.parseInt(strArray[1]);
	int sum = 0;
	for (int i = 1; i < N; i++) {
	    sum += i;
	}
	for (int i = 1; i < M; i++) {
	    sum += i;
	}
	System.out.println(sum);
    }
}