#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 */  
    unsigned long long n,m;
    cin>>n>>m;
        unsigned long long l;
        l=n*m-1;
        cout<<l<<endl;
    
    return 0;
}