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