#include <bits/stdc++.h>
using namespace std;
int main() {
  int arr[3];
  for (int i = 0; i < 3; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + 3);
  int val = arr[0] + arr[1];
  if (val <= arr[2]) {
    int res = arr[2] - val + 1;
    cout << res << endl;
  } else
    cout << "0" << endl;
}
