#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, x, y, z;
  cin >> a >> b >> c;
  int q[3] = {a, b, c};
  sort(q, q + 3, greater<int>());
  x = q[0];
  y = q[1];
  z = q[2];
  int t = z + y;
  if (t > x)
    cout << 0;
  else {
    cout << (x - t) + 1;
  }
}
