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