#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define mem(a,x) memset((a),x,sizeof (a))
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const LL LLINF = 0x3f3f3f3f3f3f3f3f;
int main() {
#ifdef _DEBUG
    freopen("data.in", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    int a,b;
    while(cin>>a>>b){
        int s=a+b-1;
        cout<<a*b-s<<endl;
    }
    return 0;
}
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