#include <bits/stdc++.h>
const int inf = 0x3f3f3f3f;
const double PI = acos(-1.0);
const double EPS = 0.0001;
using namespace std;
int n;
long long a[100010];
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%I64d", &a[i]);
  sort(a, a + n);
  long long Max = a[n - 1], sum = 0;
  for (int i = 0; i < n - 1; i++) sum += a[i];
  printf("%I64d\n", Max - sum + 1);
  return 0;
}
