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