def is_cpctf_like(s):
    if s[0] != s[2]:
        return False
    
    if s[0] == s[1] or s[0] == s[3] or s[0] == s[4]:
        return False
    
    if s[1] == s[3] or s[1] == s[4] or s[3] == s[4]:
        return False
    
    return True

def count_cpctf_like(s):
    n = len(s)
    count = 0
    
    for i in range(n):
        for j in range(i+1, n):
            for k in range(j+1, n):
                for l in range(k+1, n):
                    for m in range(l+1, n):
                        substring = s[i] + s[j] + s[k] + s[l] + s[m]
                        if is_cpctf_like(substring):
                            count += 1
    
    return count

N = int(input())
S = input().strip()

result = count_cpctf_like(S)
print(result)