#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;

// a、b、c...的数目映射为1、2、3...的数目存到数组里
int cnt[30];

int main()
{
    char s[1010];
    cin >> s+1;
    int n = strlen(s);

    for(int i = 1; i <= n; i++)
    {
        int t = s[i] - 'a' + 1;
        cnt[t]++;
    }
    sort(cnt, cnt + 26);

    int maxx = -1, minn = 2000;
    for(int i = 1; i <= 26; i++)
        if(cnt[i])
        {
            maxx = max(maxx, cnt[i]);
            minn = min(minn, cnt[i]);
        }
    cout << maxx - minn;
    return 0;
}