1980A - Problem Generator - CodeForces Solution

for _ in range(int(input())):
    n,k=map(int,input().split())
    s=input()
    z=[]
    c=0
    for i in set(s):
        z.append(s.count(i))
    c+=(7-len(z))*k
    for i in z:
        if i<k:
            c+=k-i
    print(c)