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