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