from collections import deque
n = int(input())
q = deque([i for i in range(10, 100) if int(str(i)[0]) < int(str(i)[1])])
res = []

while q and len(res) < n:
    x = q.popleft()
    res.append(x)
    y = x*10+int(str(x)[-1])
    q.append(y)

print(res[-1])