#include<stdio.h>
#include<ctype.h>
void main()
{
    int n;
    scanf("%d",&n);
    char a[100];
    for(int i=0;i<n;i++)
    {
        scanf(" %c",&a[i]);
    }
    int even,odd;
    for(int i=0;i<n;i++)
    {
        if((i%2==0)||(i==0))
        {
           even+=(int)a[i];
        }
        else
        {
            odd+=(int)a[i];
        }
    }
    int diff=even-odd;
    if(diff<0)
    {
        diff=-(diff);
    }
    printf("%d",diff);
    
    
    
    
    
    
    
    
    
    
 /*   for(int i=0;i<n;i++)
    {
        if(!(scanf(%c,&a[i])).isalpha())
        {
            printf("Invalid input");
            return;
        }
        if((i%2==0)||(i==0))
        {
           sum+=(int)a[i];
        }
        else
        {
            sum-=(int)a[i];
        }
    }
    
}