“…Solution of (3), denoted by ( ) = ( 1 ( ), 2 ( ), 1 ( ), 2 ( )) , is piecewise and continuous function: : + → 4 + , ( ) is continuous on ( , ( + 1) ], ∈ + , and ( + ) = lim → + ( ) exists. Obviously, the global existence and uniqueness of solution of (3) are guaranteed by the smoothness of = ( 1 , 2 , 3 , 4 ), where denotes the mapping defined by right side of system (2). For more details refer to [20,21].…”