#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c;
  cin >> a;
  cin >> b;
  cin >> c;
  int m, n;
  m = max(a, max(b, c));
  n = a + b + c - m;
  if (m - n >= 0) {
    cout << m - n + 1 << "\n";
  } else {
    cout << 0 << "\n";
  }
}
