#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int a[n], max = INT_MIN, sum = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d", &a[i]);
    if (a[i] > max) max = a[i];
    sum += a[i];
  }
  int x = max - (sum - max) + 1;
  printf("%d\n", x);
  return 0;
}
