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