how can I recognize face of unknown person using CNN in matlab

I have train faces of 16 people with 35 images for each person .how can I recognize face of unknown person. Please help in coding for this requirement. Here is test data code .For training I have use CNN .

load net.mat;%Train data

myFolder ='D:\FYP\Convolutions\New folder\New folder';%Image taken for attendace

filePattern = dir(fullfile(myFolder,'*.jpg'));

totalstudents=numel(filePattern)

for k = 1:totalstudents

e=fullfile(myFolder,filePattern(k).name);

ourimage=imread(e);

imgre=imresize(ourimage,[128 128]);

present(k,:)=classify(net,imgre);%net is train data and imgre is images for attendace

subplot(4,5,k)

imshow(imgre)

title(char(present(k)));

end

if I have unknown face which not train in train images then how to write code after classification or prediction to recognized that face .