#include <bits/stdc++.h>
using namespace std;
const long long M = 1e5 + 5;
int32_t main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  vector<long long> si(3);
  cin >> si[0] >> si[1] >> si[2];
  sort(si.begin(), si.end());
  if (si[0] + si[1] > si[2])
    cout << "0\n";
  else {
    cout << si[2] + 1 - si[0] - si[1] << '\n';
  }
  return 0;
}
