#include <bits/stdc++.h>
using namespace std;
int a[100];
int main() {
  cin >> a[0] >> a[1] >> a[2];
  sort(a, a + 3);
  if (a[2] < a[0] + a[1])
    cout << 0 << "\n";
  else
    cout << a[2] - a[0] - a[1] + 1 << "\n";
}
