#include <bits/stdc++.h>
#define _overload3(_1,_2,_3,name,...) name
#define FOR(i,a,b) for(int i=int(a);i<int(b);++i)
#define IFOR(i,a,b) for(int i=int(b)-1;i>=int(a);--i)
#define REP(i,n) FOR(i,0,n)
#define IREP(i,n) IFOR(i,0,n)
#define rep(...) _overload3(__VA_ARGS__,FOR,REP,)(__VA_ARGS__)
#define irep(...) _overload3(__VA_ARGS__,IFOR,IREP,)(__VA_ARGS__)
#define all(v) begin(v), end(v)
using namespace std;
using ll = long long;
using Graph2 = vector<vector<int>>;
constexpr int INF32 = 1<<29;
constexpr ll INF64 = 1LL<<60;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

int main() {
    string s;
    cin >> s;
    cout << *max_element(all(s)) - *min_element(all(s)) << endl;
    return 0;
}