#include <bits/stdc++.h>
using namespace std;

int main(){
    int a,b,c;cin >> a >> b >> c;
    int cost1 = 0,cost2 = 0;
    cost1 = b - max(a,c) + 1;
    cost2 = min(abs(a-c),min(abs(b-c),abs(a-b)));
    cout << min(cost1,cost2) << endl;
}