s c c s c s k c c s c s s s s t t k c s s s c s s k c s s s s s s s c s s s k c s s c c s s k k c s c c s k c t k c s s k k c s s c t k c s k c k c s c k c c s s s s c s t k c s s c s c s s k c c t t k c s k c c s c s s c s s k c s s c s c s s k k c s s c s c s s k c c s c s c k k c s c cs k k c k k c k c