#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int a, b, c;
  cin >> a >> b >> c;
  if (a >= (b + c)) {
    cout << abs(b + c - a) + 1 << endl;
  } else if (b >= (c + a)) {
    cout << abs(c + a - b) + 1 << endl;
  } else if (c >= (a + b)) {
    cout << abs(a + b - c) + 1 << endl;
  } else {
    cout << '0' << endl;
  }
}
