n=int(input())
ans=[' ' for _ in range(11)]
ans_=[]
letter=[' ','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z']
while n:
  new=n%26
  if new==0:
    new=26
    n+=-26
  ans_.append(new)  
  n=int(n/26)  
ans_=ans_[::-1]
for i in range(len(ans_)):
  ans[i]=letter[ans_[i]]
print(''.join(ans)) 
  