#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 */    
    unsigned long long n,m,result=0;
    scanf("%llu %llu",&n,&m);
    result = (n*m)-1;
    printf("%llu",result);
    return 0;
}