N = int(input())
N -= 1

base = []
for i in range(1, 9):
    for j in range(i + 1, 10):
        base.append(str(i) + str(j))

M = len(base)
sho, amari = divmod(N, M)

X = base[amari][-1]
ans = base[amari] + X*(sho)
print(ans)