N = 20 S = " " * N for i in range(N): S = S[1:] + "X" print(S)
Standard input is empty
X XX XXX XXXX XXXXX XXXXXX XXXXXXX XXXXXXXX XXXXXXXXX XXXXXXXXXX XXXXXXXXXXX XXXXXXXXXXXX XXXXXXXXXXXXX XXXXXXXXXXXXXX XXXXXXXXXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX