#include <bits/stdc++.h>
using namespace std;
long long iHateGeometry[100001];
int main() {
  int N;
  scanf("%d", &N);
  long long maxi = -1, sum = 0;
  for (int i = 0; i < N; i++) {
    scanf("%lld", &iHateGeometry[i]);
    sum += iHateGeometry[i];
    maxi = max(maxi, iHateGeometry[i]);
  }
  printf("%lld\n", 2 * maxi - sum + 1);
}
