#include <bits/stdc++.h>
using namespace std;
int a[3];
int main() {
  cin >> a[0] >> a[1] >> a[2];
  sort(a + 0, a + 3);
  int res = 0;
  while ((a[0] + a[1]) <= a[2]) {
    a[0]++;
    res++;
  }
  cout << res;
}
