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