Given an integer n, return *the number of strings of length n that consist only of vowels (a, e, i, o, u) and are **lexicographically sorted**.*

A string s is **lexicographically sorted** if for all valid i, s[i] is the same as or comes before s[i+1] in the alphabet.

**Example 1:**

```
```**Input:** n = 1
**Output:** 5
**Explanation:** The 5 sorted strings that consist of vowels only are ["a","e","i","o","u"].

**Example 2:**

```
```**Input:** n = 2
**Output:** 15
**Explanation:** The 15 sorted strings that consist of vowels only are ["aa","ae","ai","ao","au","ee","ei","eo","eu","ii","io","iu","oo","ou","uu"]. Note that "ea" is not a valid string since 'e' comes after 'a' in the alphabet.

**Example 3:**

**Input:** n = 33 **Output:** 66045

**Constraints:**

1 <= n <= 50

**Solution:**

```
class Solution {
public int countVowelStrings(int n) {
int a=1,e=1,i=1,o=1,u=1;
while(--n>0)
{
u=u;
o+=u;
i+=o;
e+=i;
a+=e;
}
return a+e+i+o+u;
}
}
```

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