A system has an input device for collecting gesture information of a user, a computing device for processing the gesture information collected by the input device, a memory for storing information of executive trajectories for executing various functions, and an output device for displaying the information processed by the computing device, wherein each executive trajectory is defined as an executive input for each function, if a gesture performed by the user completes one of the executive trajectories, a function corresponding to the corresponding executive trajectory is executed, wherein, if the user starts a gesture, the computing device compares a path of a trajectory of a gesture performed by the user with start paths of the executive trajectories and selects candidate trajectories having similarity higher than a preset criterion, and wherein the candidate trajectories are displayed by the output device to suggest path information of the candidate trajectories to the user.