// editor1
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int calculate_difference(char *initials){
    int even_sum=0 , odd_sum=0;
    for(char *p = initials;*p !='\0';p++){
        
        
        if((int)*p % 2==0){
            even_sum +=(int)*p;
        }else{
            odd_sum +=(int)*p;
        }
    }
    return abs(even_sum - odd_sum);
}
int main(){
    
    char initials [100]
    scanf("%s",&initials);
    printf("%d\n",calculate_difference(initials));
    
    return 0;
}