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