from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

X = []
N = int(input())
N -= 1
M = 0
for i in range(1,9):
    for j in range(i+1,10):
        X.append(10*i+j)
        M +=1

m,r = divmod(N,M)
x = str(X[r])
ans = x + x[-1]*m
print(ans)