#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base ::sync_with_stdio(false), cin.tie(NULL), cout.tie(0);
  long long int a[3];
  for (int i = 0; i < 3; i++) cin >> a[i];
  sort(a, a + 3);
  if (a[2] < a[1] + a[0])
    cout << 0;
  else
    cout << (a[2] - a[1] - a[0] + 1);
  return 0;
}
