#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 int n,m;
    scanf("%ld%ld",&n,&m);
    if(n==1 && m==1)
        printf("0");
    else if(n==1)
         printf("%ld",m-1);
        else if (m==1)
        printf("%ld",n-1);
        else
    printf("%ld",n*(m-1)+n-1);
    return 0;
}