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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    long int n,m,i,j,ans=0;
    cin>>n>>m;
    if(n==1&&m==1)
    {cout<<0;return 0;}
    if(n>1)
        i=n-1;
    if(m>1)
        j=m-1;
    ans=i+(j*n);
    cout<<ans;
    return 0;
}