str1=input('First ');
str2=input('second ');
n1=length(str1);
n2=length(str2);
%
ind=1; % indication if 0-exists
       % 1-not exists

n=n1-n2+1; % reducing the search

% Nested Loops
% ============

% External loop
for i=1:n
    if str1(i)==str2(1) % comapring the charcter i'th of str1
                        % with the first character of str2.
                        %
                        % search where to start the fine search of str2 in str1.
        ind=0;   % the substring is found  (the first character is found).  
        
        % Internal loop
        for j=1:(n2-1) % The fine search of the substring.    
            if str1(i+j)~=str2(1+j)  
                % is there a character of a substrig that is not if the string str1?
              ind=1;  % the substring doesn't exist
               break  % exit from the loop.
            end        
        end %j
    end
    
    if ind==0 % If exists?
        break  % exit from the loop
    end
    
end %i

if ind==1
    disp(['doesn-t exist']);
else
    disp(['exists']);
end