#include <bits/stdc++.h>
const int INF_INT = 0x3f3f3f3f;
const long long INF_LL = 0x7f7f7f7f;
const int MOD = 1e9 + 7;
const double eps = 1e-10;
const double pi = acos(-1);
using namespace std;
int n;
long long a[100010];
int main(int argc, char const *argv[]) {
  while (scanf("%d", &n) == 1) {
    long long maxl = 0;
    for (int i = 1; i <= n; i++) {
      scanf("%I64d", a + i);
      maxl = max(maxl, a[i]);
    }
    long long sum = 0;
    for (int i = 1; i <= n; i++) sum += a[i];
    cout << maxl - (sum - maxl) + 1 << endl;
  }
  return 0;
}
