#include <bits/stdc++.h>
using namespace std;
long long a[10];
int main() {
  for (long long i = 1; i <= 3; i++) cin >> a[i];
  sort(a + 1, a + 1 + 3);
  long long zr = 0;
  cout << max(zr, a[3] - (a[2] + a[1]) + 1);
}
