N = int(input())

A = []
for a in range(1,9):
    for b in range(a+1,10):
        A.append(10*a + b)

qu = N//len(A)
rem = N%len(A)
if rem == 0:
    qu -= 1
tail = str(A[rem-1])[-1]
ans = str(A[rem-1]) + tail*qu
print(ans)