N, K = map(int, input().split())
if K == 1:
    print(0)
elif N > K:
    print(N - K)
elif N == K:
    print(0)
else:
    print(1) N, K = map(int, input().split()) N map(int, input().split()) map int input().split() ().split () input split K if K == 1:
    print(0)
elif N > K:
    print(N - K)
elif N == K:
    print(0)
else:
    print(1) K == 1 K 1 print(0) print 0 elif N > K:
    print(N - K) N > K N K print(N - K) print N - K N K elif N == K:
    print(0) N == K N K print(0) print 0 print(1) print 1 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)
elif N > K:
    print(N - K)
elif N == K:
    print(0)
else:
    print(1)