from array import array

c = array('u', ['a', 'b', 'c', 'd'])
c[0] = 'a';
c[3] = 'J';
c[2] = 'k';
c[1] = 'R';
for z in c:
        print(z)
for k in range(0, 4):
        c[k] = chr(ord(c[k]) + 1)
for z in c:
        print(z)