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


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