#include<bits/stdc++.h>
using namespace std;

#define F first
#define S second
#define pb push_back
#define mp make_pair
#define var(X) cerr << " --> " << #X << " = " << X << endl
#define arr(a,n) for(int i=0;i<n;i++){if(i==0) cout<<"Results for array "<< #a <<"\n";cout<<a[i]<<" ";} cout<<endl
#define arr1(a,n) for(int i=1;i<=n;i++){if(i==1) cout<<"Results for array "<< #a <<"\n";cout<<a[i]<<" ";} cout<<endl

//setbase - cout << setbase (16); cout << 100 << endl; Prints 64
//setfill -   cout << setfill ('x') << setw (5); cout << 77 << endl; prints xxx77
//setprecision - cout << setprecision (4) << f << endl; Prints x.xxxx

typedef long long ll;
typedef vector<int> vi;
typedef pair<int,int> ii;
typedef vector<pair<int,int> > vii;
const double eps = 1e-10, pi = acos(-1.0);



int main()
{
	/*
	#ifndef ONLINE_JUDGE
	freopen("input.txt","r",stdin);
	freopen("out.txt","w",stdout);
	#endif
	*/
	
	int t=1,cs=1;
	//ios_base::sync_with_stdio(0); cin.tie(0);	
	//clock_t start=clock();
	//scanf("%d",&t);
	while(t--)
	{
		ll n,m,x,y,ans=LLONG_MAX;
		cin>>n>>m;
		if(n==1 && m==1)
		ans=0;
		if(n>=2)
		ans=min(ans,(n-1)+((n)*(m-1)));
		if(m>=2)
		ans=min(ans,(m-1)+((m)*(n-1)));
		cout<<ans<<"\n";
		
	}
	//clock_t end=clock();
	//cout <<"Time: " <<(double)(end-start)/CLOCKS_PER_SEC <<" seconds" <<endl;
	return 0;
}