How to draw irregular outline of MSER region?

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I have detected MSER regions as follows(Thanks a lot for Alexander Shishkov's help!)

#include <opencv2/opencv.hpp>
int main(int argc, char *argv[])
{
    Mat box = imread("box.png",1);
    MSER ms;
    vector<vector<Point>> regions;
    ms(box, regions, Mat());
    for (int i = 0; i < regions.size(); i++)
    {
        ellipse(box, fitEllipse(regions[i]), Scalar(255));
    }
    imshow("mser", box);
    waitKey(0);
    return 0;
}

Next step I try to draw irregular outlines of MSER regions which have been detected by the above code. This step I write code as follow:

int main(int argc, char *argv[])
{
    Mat box = imread("box.png",1);
    MSER ms;
    vector<vector<Point>> regions;
    ms(box, regions, Mat());
    for (int i = 0; i < regions.size(); i++)
    {
        ellipse(box, fitEllipse(regions[i]), Scalar(255));
        drawContours(box,regions,i,Scalar(0,255,255),1,8);//this was used to draw
        //irregular  outlines of MSER regions  
    }
    imshow("mser", box);
    waitKey(0);
    return 0;
}

The result of above code show that the irregular interiors of MSER regions are drawn. But, I just need draw irregular outlines of MSER regions, not interiors, how I need use the function of drawContours, what should I do?