from itertools import combinations
from collections import Counter

N=int(input())
S=list(map(str, input()))

ans = 0
for com in combinations(S, 5):
    C=Counter(com)
    if com[0] == com[2] and C[com[0]] == 2 and C[com[1]] == 1 and C[com[3]] == 1 and C[com[4]] == 1:
        ans += 1

print(ans)