import sys

sys.setrecursionlimit(10 ** 6)

int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def SI(): return sys.stdin.readline()[:-1]
def MI(): return map(int, sys.stdin.readline().split())
def MI1(): return map(int1, sys.stdin.readline().split())
def MF(): return map(float, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LF(): return list(map(float, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]

def main():
    n=II()
    aa=[]
    while n:
        a=1
        while (a+1)*(a+2)//2<=n:a+=1
        n-=a*(a+1)//2
        aa.append(a)
        #print(n,a)
    #print(aa)
    ans=""
    for i,a in enumerate(aa):
        ans+=chr(97+i)*a
    print(ans)

main()