N,K=map(int, input().split())
c=list(map(int, input().split()))
co = [0]*(N + 1)
for i in range(N):
    co[c[i]]+=1
co.sort(reverse=True)
t=0
n=0
for co in co:
    if t>=K:
        break
    t += co
    n+=1
print(n)