#include <bits/stdc++.h>
using namespace std;
int l[100000];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  int n;
  cin >> n;
  int maxi = 0;
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> l[i];
    if (l[i] > l[maxi]) maxi = i;
    sum += l[i];
  }
  long long restSides = sum - l[maxi];
  cout << l[maxi] - restSides + 1;
}
