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