alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
n = int(input())
al_list = [0,0,0,0,0,0,0]
for i in range(n // 26 //26):
    al_list[-2] += 1
    if 27 in al_list:
        digit = al_list.index(27)
        al_list[digit] = 0
        al_list[digit - 1] += 1
al_list[-1] = n // 26 % 26
while 0 in al_list:
        al_list.remove(0)
al_list = list(x-1 for x in al_list)
al_list.append(n % 26)
for j in al_list:
    print(alphabet[j], end = '')