acm头文件

#pragma comment(linker, "/STACK:1024000000,1024000000")
#pragma GCC optimize(3,"Ofast","inline")
#include <bits/stdc++.h>

using namespace std;

#define rep(i , a , b) for(register int i=(a);i<=(b);i++)
#define per(i , a , b) for(register int i=(a);i>=(b);i--)
#define sqr(x) (x*x)
#define mem(a,x) memset(a,x,sizeof(a))
#define ls (rt<<1)
#define rs (rt<<1|1)
#define ios ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fi first
#define se second
#define pb push_back
#define mp make_pair

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int , int> pii;
typedef unordered_map<int,int> un_map;
const int inf = 0x3f3f3f3f;
const double pi = acos(-1);
const double eps=1e-8;
const int mod = 1e9+7;
const int maxn = 1005;
inline void read(ll &x) {
    x = 0;
    static int p;
    p = 1;
    static char c;
    c = getchar();
    while (!isdigit(c)) {
        if (c == '-')p = -1;
        c = getchar();
    }
    while (isdigit(c)) {
        x = (x << 1) + (x << 3) + (c - 48);
        c = getchar();
    }
    x *= p;
}
inline void print(ll x) {
    static int cnt;
    static int a[30];
    cnt = 0;
    do {
        a[++cnt] = x % 10;
        x /= 10;
    } while (x);
    for (int i = cnt; i >= 1; i--)putchar(a[i] + '0');
    puts("");
}

ll a,b;

int main() {

#ifdef LOCAL
    freopen("1.txt", "r", stdin);
    //freopen(".out", "w", stdout);
#endif
    read(a);
    read(b);
    print(a * b - a - b);
    return 0;
}