c = input ('请输入字母','s');
if c >= 'A' && c <= 'Z'
    disp(lower(c));
elseif  c >= 'a' && c <= 'z'
    disp(upper(c));
elseif c >='0' && c <='9'
    disp(str2double(c)^2);
else
    disp(c);
end