#include <bits/stdc++.h>
using namespace std;
int _I() {
  int x;
  scanf("%d", &x);
  return x;
}
int dirX[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dirY[] = {0, 1, 0, -1, 1, -1, -1, 1};
int rX[] = {1, 1, 2, 2, -1, -1, -2, -2};
int rY[] = {2, -2, 1, -1, 2, -2, +1, -1};
long long ar[300003];
void Do() {
  long long n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> ar[i];
  sort(ar, ar + n);
  long long mx = ar[n - 1], c = 0, mx1;
  int ver = 1;
  for (int i = 0; i < n - 1; i++) {
    c += ar[i];
    if (c >= mx && ver == 1) mx1 = c - ar[i], c = ar[i], ver += 1;
  }
  long long ans, pp[4];
  if (ver == 2) {
    pp[0] = c;
    pp[1] = mx;
    pp[2] = mx1;
    sort(pp, pp + 3);
    ans = pp[2] - (pp[0] + pp[1]) + 1;
  } else
    ans = mx - c + 1;
  cout << ans << endl;
}
int main() {
  Do();
  return 0;
}
