#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9 + 7;
const long long inf18 = 1e18 + 7;
const int N = 1e5 + 5;
int main() {
  int n;
  cin >> n;
  int a[n + 2];
  int ma = -1;
  long long s = 0;
  for (int i = 0; i < n; ++i) cin >> a[i], s += a[i], ma = max(ma, a[i]);
  cout << ma - (s - ma) + 1 << endl;
}
