#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1);
const int INF = 2e9;
const long long MOD = 1e9 + 7;
const int MAXN = 1e5 + 2;
const int MN = 1e6 + 3;
long long aa[MAXN];
long long sum = 0;
long long maxi = 0;
int main() {
  int n;
  scanf("%d", &n);
  sum = 0;
  maxi = 0;
  for (int(i) = (0); (i) < (n); ++(i)) {
    scanf("%I64d", &aa[i]);
    sum += aa[i];
    maxi = max(maxi, aa[i]);
  }
  long long ans = 0;
  ans = 2 * maxi + 1 - sum;
  ans = max(ans, 1LL);
  printf("%I64d", ans);
  return 0;
}
