import sys
input = sys.stdin.readline
from collections import *

N = int(input())-1
l = []

for a in range(1, 10):
    for b in range(a+1, 10):
        l.append(10*a+b)

s, a = divmod(N, 36)
ans = str(l[a])+str(l[a])[-1]*s
print(ans)