#include <bits/stdc++.h>
using namespace std;
int main(int argc, char *argv[]) {
  vector<int> Length(3);
  for (int i = 0; i < 3; ++i) {
    scanf("%d", &Length[i]);
  }
  sort(Length.begin(), Length.end());
  printf("%d\n", max(0, Length[2] - (Length[0] + Length[1]) + 1));
  return 0;
}
