#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 n, m;
    scanf("%lld%lld", &n, &m);
    printf("%lld", n*m - 1);
    return 0;
}