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