#include <bits/stdc++.h>
using namespace std;
long long INF = 9223372036854775807;
int md = 100000000;
const int WHITE = 0;
const int BLACK = 1;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  vector<int> m;
  int a;
  cin >> a;
  m.push_back(a);
  cin >> a;
  m.push_back(a);
  cin >> a;
  m.push_back(a);
  sort(m.begin(), m.end());
  if (m[0] + m[1] <= m[2])
    cout << m[2] - m[1] - m[0] + 1 << endl;
  else
    cout << 0 << endl;
  return 0;
}
