Problem A
H-Index
                                                                                    
   
      In research, it is tough to determine how good of a researcher you are. One way that people determine how good you are is by looking at your $H$-Index.
Each paper has a certain number of citations. Your $H$-Index is the largest number $H$ such that you have $H$ papers with at least $H$ citations. Given the number of citations on each paper you have written, what is your $H$-Index?
Input
The first line of input contains a single integer $n$ ($1 \leq n \leq 100\, 000$), which is the number of papers you have written.
The next $n$ lines describe the papers. Each of these lines contains a single integer $c$ ($0 \leq c \leq 1\, 000\, 000\, 000$), which is the number of citations that this paper has.
Output
Display your $H$-Index.
| Sample Input 1 | Sample Output 1 | 
|---|---|
| 5 7 1 2 1 5 | 2 | 
| Sample Input 2 | Sample Output 2 | 
|---|---|
| 5 7 1 3 1 5 | 3 | 
| Sample Input 3 | Sample Output 3 | 
|---|---|
| 3 4 2 3 | 2 | 
