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


int main() {
    long long N,M;
    cin>>N>>M;
    cout<<(long long)N*M-1<<endl;
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}