#include <bits/stdc++.h>
using namespace std;
const int mm = 100000 + 10;
int a[mm];
int main(int argc, char* argv[]) {
  int i, n, maxn, sum, ans;
  while (cin >> n) {
    maxn = sum = 0;
    for (i = 0; i < n; i++) {
      cin >> a[i];
      sum += a[i];
      if (a[i] > maxn) {
        maxn = a[i];
      }
    }
    sum -= maxn;
    ans = maxn - sum + 1;
    cout << ans << endl;
  }
  return 0;
}
