#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[3];
  for (int i = 0; i < 3; i++) {
    cin >> a[i];
  }
  sort(a, a + 3);
  if (a[2] < a[0] + a[1]) {
    cout << 0 << endl;
  } else {
    cout << a[2] - a[1] - a[0] + 1 << endl;
  }
  return 0;
}
