#include <bits/stdc++.h>
using namespace std;
long long a[3], t, mx, sum;
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> t;
    sum += t;
    if (t > mx) mx = t;
  }
  sum -= mx;
  cout << mx - sum + 1 << endl;
}
