from collections import deque

N = int(input())

deq = deque()
cnt = 0
for a in range(1,9):
    for b in range(a+1,10):
        deq.append((10*a + b, b))
        cnt += 1

if N <= cnt:
    print(deq[N-1])
else:
    while cnt < N:
        a,b = deq.popleft()
        X = 10*a + b
        deq.append((X,b))
        cnt += 1
        if cnt == N:
            print(X)
            break