#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<int> abc(3);
  for (int i = 0; i < 3; i++) cin >> abc[i];
  sort(abc.begin(), abc.end());
  if (abc[0] + abc[1] > abc[2]) return cout << 0 << endl, 0;
  cout << abc[2] - abc[1] - abc[0] + 1 << endl;
}
