#include <bits/stdc++.h>
using namespace std;
int n;
long long ans, a[200100], sum, mx;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n;
  for (int i = 0; i < n; i++) cin >> a[i], sum += a[i], mx = max(mx, a[i]);
  ans = mx + mx + 1 - sum;
  cout << ans;
  return 0;
}
