#include <bits/stdc++.h>
using namespace std;
vector<int> v;
int main() {
  int a, b, c;
  cin >> a >> b >> c;
  if ((a + b > c) && (b + c > a) && (c + a > b))
    cout << "0\n";
  else {
    v.push_back(a);
    v.push_back(b);
    v.push_back(c);
    sort(v.begin(), v.end());
    a = v[0];
    b = v[1];
    c = v[2];
    cout << (c - (a + b) + 1) << "\n";
  }
}
