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

int main() {
    long int n,m;
    scanf("%ld%ld",&n,&m);
    long long sum = n*m;
    printf("%lld\n",sum-1);

    /* Enter your code here. Read input from STDIN. Print output to STDOUT */    
    return 0;
}