#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>

int main() {

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
   long long int n,m,ans=0;
    scanf("%lld",&n);
    scanf("%lld",&m);
    if(n!=1 || m!=1)
        {
    ans=(n*m)-1;
    }
    printf("%lld",ans);
    return 0;
}