/*
注意！！！题目的理解很重要，我当初就是因为题意理解有误，一直WA
We shouldn't count as missed meals on the arrival day before Vasiliy's arrival and meals on the departure day after he left.
这句话表明了：如果在抵达的那天，或者离开的那天，没有吃满3顿，那么这两种少吃的情况，并不算在计算的顿数中
*/
#include <iostream>
typedef long long ll;
using namespace std;
int main()
{
cin.tie(0);
cin.sync_with_stdio(false);
ll b, d, s;
while (cin >> b >> d >> s)
{
ll ans = 0, tp = max(b, max(d, s));
tp--;
if (tp > b) ans += tp - b;
if (tp > d) ans += tp - d;
if (tp > s) ans += tp - s;
cout << ans << endl;
}
return 0;
}
