n = int(input())
s = ["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"]
cnt = 0

for i in range(26):
    for j in range(26):
        for k in range(26):
            for l in range(26):
                cnt+=1
                if cnt<n:
                    print("a"+s[i]+s[j]+s[k]+s[l]+"a")
                else:
                    print("admin")
                    exit(0)