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

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