a = [i for i in range(3)]

print(a)

a = [i for i in range(2, -1, -1)]

print(a)

s = "nguyen to son"

length = len(s)

for i in range(0, length):
    print("%3d: %c" % (i, s[i]))

print()

for i in range(1, length+1, 1):
    print("%3d: %c" % (-i, s[-i]))

print()

for i in range(length-1, -1, -1):
    print("%3d: %c" % (i, s[i]))