dic = {}
alphabets = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
for i in range(26):
    dic[(i)%26] = alphabets[i]

#print(dic)
    
def base_n(num_10,n):
    str_n = []
    while num_10:
        str_n.append(num_10%n)
        num_10 //= n
    return str_n

N = int(input())
nums_reverse = base_n(N, 26)
#print(nums_reverse)
ans_reverse = []

for i in range(len(nums_reverse)):
    if i == 0:
        ans_reverse.append(dic[(nums_reverse[i])%26])
    else:
        ans_reverse.append(dic[(nums_reverse[i]-1)%26])
#print(ans_reverse)
print(''.join(ans_reverse[::-1]))