P s st b

P s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st bP s st b