#include <bits/stdc++.h>
using namespace std;
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y / 2;
    x = (x * x) % p;
  }
  return res;
}
void solve() {
  long long int a[3];
  cin >> a[0] >> a[1] >> a[2];
  sort(a, a + 3);
  long long int x = a[0] + a[1] - a[2];
  if (x > 0) {
    cout << 0 << "\n";
    return;
  } else {
    cout << a[2] + 1 - (a[0] + a[1]) << "\n";
    return;
  }
}
int main() {
  long long int t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
