function DFT_IFT(x,h, length_of_set)
    
    N  = floor(length_of_set);
    X  = fft(x, N); H = fft(h, N);
    Y  = X .* H;
    n  = 0:N-1;
    y  = ifft(Y, N); 
    figure
    stem(n,y)
    title ([' DFT/IDFT with length ' num2str(N) ])
    axis ([0 36 0 7])
    xlabel 'n'
    ylabel 'y[n]'