#include <bits/stdc++.h>
#define ll long long
#define maxn 100005
#define slld(t) scanf("%lld",&t)
#define sd(t) scanf("%d",&t)
#define pd(t) printf("%d\n",t)
#define plld(t) printf("%lld\n",t)
#define fo(i,n) for(long long i=0;i<n;i++)
using namespace std;
ll an(ll m,ll n){
  //  cout<<m<<" "<<n<<endl;
    if(m==1)return n-1;
    if(n==1)return m-1;
    if(m>=n){
        if(m%2==0){
            return 1+  2*an(m/2,n);
        }
        return 1+ an(m/2,n) + an(m/2 + 1,n);
    }
    return an(n,m);
}
void solve(){
    ll m,n;
    slld(m);
    slld(n);
    ll ans=m*n - 1;
    plld(ans);

}
int main(){
    int t;
    t=1;
    while(t--)solve();
}