Draw Rectangle from Webcam with 2 largest object

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I need to draw rectangle with 2 largest object from webcam. I already got to draw contours with 2 largest object from webcam but now i confuse in how to draw 2 largest Rectangle. Someone can show me the code Please~

//find and draw contours
void showconvex(Mat &thresh,Mat &frame)
{

    int largestIndex = 0;
    int largestContour = 0;
    int secondLargestIndex = 0;
    int secondLargestContour = 0;

    vector<vector<Point> > contours;
    vector<Vec4i> hierarchy;

    //find contours
    findContours(thresh, contours, hierarchy, CV_RETR_TREE, CV_CHAIN_APPROX_SIMPLE);

    /// Find the convex hull object for each contour
    vector<vector<Point> >hull(contours.size());
    vector<vector<int> >inthull(contours.size());
    vector<vector<Vec4i> >defects(contours.size());

    for (int i = 0; i < contours.size(); i++)
    {
        convexHull(Mat(contours[i]), hull[i], false);
        convexHull(Mat(contours[i]),inthull[i], false);
        if (inthull[i].size()>3)
        convexityDefects(contours[i], inthull[i], defects[i]);
    }

    //find 2 largest contour
    for( int i = 0; i< contours.size(); i++ )
    {
        if(contours[i].size() > largestContour)
        {
            secondLargestContour = largestContour;
            secondLargestIndex = largestIndex;
            largestContour = contours[i].size();
            largestIndex = i;
        }
        else if(contours[i].size() > secondLargestContour)
        {
            secondLargestContour = contours[i].size();
            secondLargestIndex = i;
        }
    }
        //show contours of 2 biggest and hull as well
    if(contours.size()>0)
        {
            //check for contouraea function if error occur
            //draw the 2 largest contour using previously stored index.
            drawContours(frame, contours, largestIndex, CV_RGB(0,255,0), 2, 8, hierarchy);
            drawContours(frame, contours, secondLargestIndex, CV_RGB(0,255,0), 2, 8, hierarchy);
        }
}