import sys
sys.set_int_max_str_digits(0)

N = int(input())

cnt = 0
for c in range(1<<60):
    for a in range(1, 9):
        for b in range(a+1, 10):
            cnt += 1
            if cnt == N:
                ans = 10*a+b
                for _ in range(c):
                    ans *= 10
                    ans += b
                exit(print(ans))