n,k = map(int,input().split())

if k == 1:
    result = 0
else:
    result = n - k

print(result) n,k = map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split k if k == 1:
    result = 0
else:
    result = n - k k == 1 k 1 result = 0 result 0 result = n - k result n - k n k print(result) print result result = 0 0 result n,k = map(int,input().split()) map(int,input().split()) n result = n - k n - k result k = map(int,input().split()) map(int,input().split()) k
n,k = map(int,input().split())

if k == 1:
    result = 0
else:
    result = n - k

print(result)