#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define INF 100000000000
using namespace std;

long long minn(long long a, long long b) {
    return (a < b ? a : b);
}

long long find(long long n, long long m) {
    if(n == 1 & m == 1)
        return 0;
    if(n <= 0 || m <= 0)
        return INF;
    if(n == 1)
        return (m-1);
    if(m == 1)
        return (n-1);
    if(minn(n, m) == n) {
        long long a = n;
        n = m;
        m = a;
    }
    return ((n-1) + n*(m-1));
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    long long n, m, a, b;
    cin >> n >> m;
    cout << find(n, m);
    return 0;
}