A computing unit computes a computed value for input data. A comparing unit compares the computed value of the computing unit with a computed value of another node which is included in an input/output set. An output unit outputs the computed value as output data of a node itself when the result of the comparison by the comparing unit shows that the computed value matches either one of computed values. When the computed value does not match any one of the computed values of other nodes, a transferring unit adds the computed value of the node itself to the input/output set, and transfers the input/output set to another node.