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