#include <bits/stdc++.h>
using namespace std;
int n;
long long a, maxnum, sum;
int main() {
  scanf("%d", &n);
  for (register int i = 1; i <= n; i++)
    scanf("%d", &a), maxnum = max(maxnum, a), sum += a;
  cout << maxnum * 2 - sum + 1 << endl;
  return 0;
}
