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*/



#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<queue>
#include<set>
#include<map>
#include<stack>
#include<time.h>
#include<cstdlib>
#include<cmath>
#include<list>
using namespace std;
#define MAXN 10000006
#define eps 0
#define For(i,a,b) for(int i=a;i<=b;i++)
#define Fore(i,a,b) for(int i=a;i>=b;i--)
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
#define mkp make_pair
#define pb push_back
#define cr clear()
#define sz size()
#define met(a,b) memset(a,b,sizeof(a))
#define iossy ios::sync_with_stdio(false)
#define fr freopen
#define pi acos(-1.0)
#define Vector Point
#define fir first
#define sec second
#define it_s_too_hard main
const long long inf=1LL<<62;
const int iinf=1<<30;
const double dinf=1e17;
const int Mod=1e9+7;
typedef long long ll;
typedef long double ld;
const int MAXBUF = 10000;
char buf[MAXBUF], *ps = buf, *pe = buf+1;
bool isdigit(char n) {
    if (n >= '0' && n <= '9') return true;
    return false;
}
inline void rnext(){
    if(++ps == pe)
        pe = (ps = buf)+fread(buf,sizeof(char),sizeof(buf)/sizeof(char),stdin);
}
template <class T>
inline bool in(T &ans){
    ans = 0;
    T f = 1;
    if(ps == pe) return false;//EOF
    do{
        rnext();
        if('-' == *ps) f = -1;
    }while(!isdigit(*ps) && ps != pe);
    if(ps == pe) return false;//EOF
    do{
        ans = (ans<<1)+(ans<<3)+*ps-48;
        rnext();
    }while(isdigit(*ps) && ps != pe);
    ans *= f;
    return true;
}
const int  MAXOUT=10000;
char bufout[MAXOUT], outtmp[50],*pout = bufout, *pend = bufout+MAXOUT;
inline void write(){
    fwrite(bufout,sizeof(char),pout-bufout,stdout);
    pout = bufout;
}
inline void out_char(char c){ *(pout++) = c;if(pout == pend) write();}
inline void out_str(char *s){
    while(*s){
        *(pout++) = *(s++);
        if(pout == pend) write();
    }
}
template <class T>
inline void out_int(T x) {
    if(!x){
        out_char('0');
        return;
    }
    if(x < 0) x = -x,out_char('-');
    int len = 0;
    while(x){
        outtmp[len++] = x%10+48;
        x /= 10;
    }
    outtmp[len] = 0;
    for(int i = 0, j = len-1; i < j; i++,j--) swap(outtmp[i],outtmp[j]);
    out_str(outtmp);
}
inline ll lowbit(ll x){
    return x&(-x);
}
int dcmp(ld x){
    if(fabs(x)<=eps) return 0;
    return x<0?-1:1;
}
struct Point{
	ll x,y;
	Point(ll x=0,ll y=0):x(x),y(y) {}
	Point operator - (const Point &a)const {return Point(x-a.x,y-a.y);}
	Point operator + (const Point &a)const {return Point(x+a.x,y+a.y);}
	bool operator == (const Point &a)const {return x==a.x&&y==a.y;}
	bool operator <  (const Point &a)const {if(x==a.x) return y<a.y;return x<a.x;}
};
ll Cross(Vector a,Vector b){ return a.x*b.y-a.y*b.x;}
ll Dot(Vector a,Vector b){ return a.x*b.x+a.y*b.y;}
bool on_seg(Point p,Point a,Point b){
	if(a==p || b==p) return 1;
	return Cross(p-a,b-a)==0 && Dot(p-a,b-a)>0;
}
bool Insect(Point p1,Point p2,Point p3,Point p4){
	if(on_seg(p1,p3,p4)|| on_seg(p2,p3,p4) || on_seg(p3,p1,p2) || on_seg(p4,p1,p2)) return 1;
	ll c1=Cross(p2-p1,p3-p1),c2=Cross(p2-p1,p4-p1);
	ll c3=Cross(p4-p3,p2-p3),c4=Cross(p4-p3,p1-p3);
	return c1*c2<0 && c3*c4<0;
}
int ConvexHull(Point *p,int n,Point *ch){
	int m=0;
	sort(p+1,p+1+n);
	For(i,1,n){
		while(m>1 && Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
		ch[m++]=p[i];
	}
	int k=m;
	Fore(i,n,1){
		while(m>k && Cross(ch[m-1]-ch[m-2],p[i]-ch[m-2])<=0) m--;
		ch[m++]=p[i];
	}
	if(n>1) m--;
	return m;
}
int a,b;
void I_can_t_solve_it(){
	cin>>a>>b;
	cout<<a*b-a-b+1<<endl;
}
int it_s_too_hard(){
	int t=1;
	iossy;
	For(i,1,t){
		I_can_t_solve_it();
	}
	return 0;
}


Measured memory_bytes: 256