#include <bits/stdc++.h>
using namespace std;
int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int a, b, c;
  cin >> a >> b >> c;
  if (a >= b && a >= c) {
    cout << max(a - b - c + 1, 0) << endl;
  } else if (b >= a && b >= c) {
    cout << max(b - a - c + 1, 0) << endl;
  } else
    cout << max(c - a - b + 1, 0) << endl;
}
