#include<bits/stdc++.h>
using namespace std;
long long a,b;
inline long long read(){
	long long x=0,f=1;char c=getchar();
	while(c<'0') f^=(c=='-'),c=getchar();
	while(c>'/') x=(x<<3)+(x<<1)+(c^'0'),c=getchar();
	return f?x:-x;
}
int main(){
	a=read();
	b=read();
	cout<<a*b-a-b<<endl;
    return 0;
}