#include <bits/stdc++.h>
using namespace std;
const int maxn = 100 * 1000 + 5;
long long n, l[maxn];
long long sum, ans = -1;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> l[i], sum += (long long)l[i];
  for (int i = 0; i < n; i++) ans = (long long)max(ans, (2 * l[i] - sum));
  cout << (long long)ans + 1 << endl;
  return 0;
}
