#include <bits/stdc++.h>
using namespace std;
int main() {
  int a[5];
  for (int i = 0; i < 3; i++) cin >> a[i];
  sort(a, a + 3);
  int ans;
  if (a[0] + a[1] > a[2])
    ans = 0;
  else {
    ans = a[2] - a[0] - a[1] + 1;
  }
  cout << ans;
  return 0;
}
