-(void) setCenterofScreen:(CGPoint) position{
    CGSize screenSize = [[CCDirector sharedDirector]winSize];

    float x = MAX(position.x,screenSize.width/2);
    float y = MAX(position.y, screenSize.height/2);

    x = MIN(x, theMap.mapSize.width * theMap.tileSize.width - screenSize/2);
    y = MIN(y, theMap.mapSize.height * theMap.tileSize.height - screenSize/2);

    CGPoint goodPoint = ccp(x,y);

    CGPoint centerOfScreen = ccpAdd(screenSize.width/2, screenSize.height/2);
    CGPoint difference = ccpSub(centerOfScreen, goodPoint);
    self.position = difference;