#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, r;
  int res = 0;
  cin >> a >> b >> c;
  if ((a + b) <= c) {
    r = c - (a + b);
    for (int i = 0; i <= r; i++) {
      res++;
    }
  }
  if ((a + c) <= b) {
    r = b - (a + c);
    for (int i = 0; i <= r; i++) {
      res++;
    }
  }
  if ((c + b) <= a) {
    r = a - (c + b);
    for (int i = 0; i <= r; i++) {
      res++;
    }
  }
  cout << res;
  return 0;
}
