Buggy python submission (verdict: Runtime Error):
import sys,collections as cl,bisect as bs
sys.setrecursionlimit(100000)
input = sys.stdin.readline
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
	return list(map(int,input().split()))
def m(): #複数文字
	return map(int,input().split())
def onem(): #Nとかの取得
	return int(input())
def s(x): #圧縮
	a = []
	if len(x) == 0:
		return []
	aa = x[0]
	su = 1
	for i in range(len(x)-1):
		if aa != x[i+1]:
			a.append([aa,su])
			aa = x[i+1]
			su = 1
		else:
			su += 1
	a.append([aa,su])
	return a
def jo(x): #listをスペースごとに分ける
	return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
	return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return True
    else:
        return False

def pow_k(x, n):
    ans = 1
    while n:
        if n % 2:
            ans *= x
        x *= x
        n >>= 1
    return ans

"""
def nibu(x,n,r):
	ll = 0
	rr = r
	while True:
		mid = (ll+rr)//2

	if rr == mid:
		return ll
	if (ここに評価入れる):
		rr = mid
	else:
		ll = mid+1
"""

n = onem()
ans = ""
while True:
	if n <= 26:
		ans = chr(96+n) + ans
		break
	else:
		po = n % 26
		if po == 0:
			po = 26
		ans = chr(96+po) + ans
		n //= 26
print(ans)

import sys,collections as cl,bisect as bs
sys.setrecursionlimit(100000)
input = sys.stdin.readline
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
	return list(map(int,input().split()))
def m(): #複数文字
	return map(int,input().split())
def onem(): #Nとかの取得
	return int(input())
def s(x): #圧縮
	a = []
	if len(x) == 0:
		return []
	aa = x[0]
	su = 1
	for i in range(len(x)-1):
		if aa != x[i+1]:
			a.append([aa,su])
			aa = x[i+1]
			su = 1
		else:
			su += 1
	a.append([aa,su])
	return a
def jo(x): #listをスペースごとに分ける
	return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
	return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return True
    else:
        return False

def pow_k(x, n):
    ans = 1
    while n:
        if n % 2:
            ans *= x
        x *= x
        n >>= 1
    return ans

"""
def nibu(x,n,r):
	ll = 0
	rr = r
	while True:
		mid = (ll+rr)//2

	if rr == mid:
		return ll
	if (ここに評価入れる):
		rr = mid
	else:
		ll = mid+1
"""

n = onem()
ans = ""
while True:
	if n <= 26:
		ans = chr(96+n) + ans
		break
	else:
		po = n % 26
		if po == 0:
			po = 26
		ans = chr(96+po) + ans
		n //= 26
print(ans)



Fixed submission:
import sys,collections as cl,bisect as bs
sys.setrecursionlimit(100000)
input = sys.stdin.readline
mod = 10**9+7
Max = sys.maxsize
def l(): #intのlist
	return list(map(int,input().split()))
def m(): #複数文字
	return map(int,input().split())
def onem(): #Nとかの取得
	return int(input())
def s(x): #圧縮
	a = []
	if len(x) == 0:
		return []
	aa = x[0]
	su = 1
	for i in range(len(x)-1):
		if aa != x[i+1]:
			a.append([aa,su])
			aa = x[i+1]
			su = 1
		else:
			su += 1
	a.append([aa,su])
	return a
def jo(x): #listをスペースごとに分ける
	return " ".join(map(str,x))
def max2(x): #他のときもどうように作成可能
	return max(map(max,x))
def In(x,a): #aがリスト(sorted)
    k = bs.bisect_left(a,x)
    if k != len(a) and a[k] ==  x:
        return True
    else:
        return False

def pow_k(x, n):
    ans = 1
    while n:
        if n % 2:
            ans *= x
        x *= x
        n >>= 1
    return ans

"""
def nibu(x,n,r):
	ll = 0
	rr = r
	while True:
		mid = (ll+rr)//2

	if rr == mid:
		return ll
	if (ここに評価入れる):
		rr = mid
	else:
		ll = mid+1
"""

n = onem()
ans = ""
while True:
	if n <= 26:
		ans = chr(96+n) + ans
		break
	else:
		po = n % 26
		if po == 0:
			po = 26
		ans = chr(96+po) + ans
		n //= 26
		if po == 26:
			n -= 1
print(ans)