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

ans.sort()

n = int(input())

c = (n-1) // 36
n %= 36

if n == 0:
    n = 36
res  = ans[n-1]
res = str(res) + str(res)[-1] * c
print(res)