#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a = 0, b = 0;
  int n;
  scanf("%d", &n);
  while (n--) {
    long long tmp;
    scanf("%lld", &tmp);
    if (tmp > a)
      b += a, a = tmp;
    else
      b += tmp;
  }
  printf("%lld\n", a - b + 1);
  return 0;
}
