X = []
for a in range(1, 10):
    for b in range(a+1, 10):
        X.append((a, b))

n = int(input())
q, r = divmod(n-1, 36)

i = 0
a, b = X[r]
ans = a * pow(10, q+1)
for i in range(q+1):
    ans += b * pow(10, i)
print(ans)