import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main
{
    static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    }
    static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.math.BigInteger; BigInteger java.math import java.util.StringTokenizer; StringTokenizer java.util public class Main
{
    static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    }
    static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    }
} Main static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    } nCr {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    } return fact(n).divide(fact(r).multiply(fact(n - r))); fact(n).divide(fact(r).multiply(fact(n - r))) fact(n).divide fact(n) fact n fact(r).multiply(fact(n - r)) fact(r).multiply fact(r) fact r fact(n - r) fact n - r n r int n n int r r static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    } fact {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    } BigInteger res =  new BigInteger("1"); res new BigInteger("1") for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i)); int i = 2; int i = 2; i 2 i <= n i n i++ i++ i res = res.multiply(BigInteger.valueOf(i)); res = res.multiply(BigInteger.valueOf(i)) res res.multiply(BigInteger.valueOf(i)) res.multiply res BigInteger.valueOf(i) BigInteger.valueOf BigInteger i return res; res int n n public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    } main {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    } FastReader obj = new FastReader(); obj new FastReader() int n = obj.nextInt() n obj.nextInt() obj.nextInt obj m = obj.nextInt(); m obj.nextInt() obj.nextInt obj System.out.println(nCr(n,2).add(nCr(m,2))) System.out.println System.out System System.out nCr(n,2).add(nCr(m,2)) nCr(n,2).add nCr(n,2) nCr n 2 nCr(m,2) nCr m 2 String args[] args static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    } FastReader BufferedReader br; br StringTokenizer st; st public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        } FastReader {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        } br = new BufferedReader(new
                    InputStreamReader(System.in)) br new BufferedReader(new
                    InputStreamReader(System.in)) String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        } next {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        } while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            } try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } IOException e {
                    e.printStackTrace();
                } e.printStackTrace() e.printStackTrace e {
                    st = new StringTokenizer(br.readLine());
                } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        } nextLine {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        } String str = ""; str "" try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                str = br.readLine();
            } str = br.readLine() str br.readLine() br.readLine br return str; str public class Main
{
    static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    }
    static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    }
} public class Main
{
    static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    }
    static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class Main
{
    static BigInteger nCr(int n, int r)
    {
        return fact(n).divide(fact(r).multiply(fact(n - r)));
    }
    static BigInteger fact(int n)
    {
        BigInteger res =  new BigInteger("1");
        for (int i = 2; i <= n; i++)
           res = res.multiply(BigInteger.valueOf(i));
        return res;
    }
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
    public static void main(String args[])
    {
        FastReader obj = new FastReader();
        int n = obj.nextInt(),m = obj.nextInt();

        System.out.println(nCr(n,2).add(nCr(m,2)));
    }
}
