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