#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, ans, n;
  n = 3;
  int ar[n];
  for (i = 0; i < n; i++) {
    cin >> ar[i];
  }
  sort(ar, ar + n);
  if (ar[0] + ar[1] > ar[2]) {
    cout << 0 << "\n";
  } else {
    ans = ar[2] - (ar[0] + ar[1]);
    cout << ans + 1 << "\n";
  }
  return 0;
}
