#include <bits/stdc++.h>
using namespace std;
int main(void) {
  long long n, max1 = 0, sum = 0, temp1;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> temp1;
    sum += temp1;
    if (max1 < temp1) max1 = temp1;
  }
  sum -= max1;
  cout << max1 - sum + 1;
  return 0;
}
