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


int main() {
   long int n,m;
  cin>>n>>m;
  long int cuts=m-1;
    for(long int i=0;i<m;++i)
      {
      cuts=n-1+cuts;
      }
  cout<<cuts;
    return 0;
}