how to search with no of occurences in factor in R? : Find the date on which three movies had launched on the same day and store it in the variable date_three

releasedate<-count(bollywood$Rdate)

> releasedate

            x freq
1  01-05-2015    1
2  02-10-2015    2
3  03-07-2015    1
4  04-09-2015    1
5  04-12-2015    1
6  05-06-2015    1
7  06-02-2015    1
8  06-03-2015    1
9  07-08-2015    1
10 08-05-2015    2
11 09-01-2015    1
12 09-10-2015    1
13 10-04-2015    1
14 11-09-2015    1
15 12-06-2015    1
16 12-11-2015    1
17 13-02-2015    1
18 13-03-2015    1
19 14-08-2015    1
20 15-05-2015    1
21 16-01-2015    1
22 16-10-2015    1
23 17-04-2015    1
24 17-07-2015    1
25 18-09-2015    1
26 18-12-2015    2
27 19-06-2015    1
28 20-02-2015    1
29 20-03-2015    1
30 21-08-2015    2
31 22-05-2015    1
32 22-10-2015    1
33 23-01-2015    2
34 25-09-2015    2
35 26-06-2015    1
36 27-02-2015    2
37 27-11-2015    1
38 28-05-2015    1
39 28-08-2015    1
40 30-01-2015    2
41 30-10-2015    3
42 31-07-2015    1

>subset(releasedate$x,releasedate$freq==3)
>[1] 30-10-2015
42 Levels: 01-05-2015 02-10-2015 03-07-2015 04-09-2015 04-12-2015 ... 31-07-2015

Is there any other way I can search elements in vector by their no of occurence ?