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