N, K = map(int, input().split(" "))
if K == 1:
    print(0)
    exit()
print(str(N - K))
 N, K = map(int, input().split(" ")) N map(int, input().split(" ")) map int input().split(" ") ().split () input split " " K if K == 1:
    print(0)
    exit() K == 1 K 1 print(0) print 0 exit() exit print(str(N - K)) print str(N - K) str N - K N K K = map(int, input().split(" ")) map(int, input().split(" ")) K N, K = map(int, input().split(" ")) map(int, input().split(" ")) N
N, K = map(int, input().split(" "))
if K == 1:
    print(0)
    exit()
print(str(N - K))

