It's a holiday season for all school students around the world! Unfortunately, Mahamba is busy preparing for International Olympiad in Informatics, which will be held in Tehran, Iran. He is now facing a new challenge from his teacher Aceka, and it goes something like this:
You have a string x of length N, which consists of small English letters. You have to find the number of indexes a, b, c and d, such that 1<=a<b<c<d<=N and xa==xc, as well as xb==xd.
He is baffled and definitely needs some help. So, you, the best programmer in Lalalandia, decided to give him a hand!
Input format
The first line contains the number N - the length of a string x. The second line contains the string x itself.
Output format
The first and only line should contain the answer to the problem.
Constraints
1<=N<=2000
The string x only contains small English letters.
There are only 2 variants: (a=1,b=2,c=3,d=4) and (a=2,b=3,c=4,d=5)