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

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