#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;
  } else {
    cout << arr[2] - arr[1] - arr[0] + 1;
  }
}
