import sys, math
input = lambda: sys.stdin.readline()[:-1]
def MI(): return map(int, input().split())
inf = 10**18

n, = MI()
n-=1
p = n//36 # 桁数-2
q = n%36

res = []
for a in range(1, 10):
    for b in range(a+1, 10):
        x = 10*a + b
        for c in range(1):
            res.append(x)
            x = 10*x + b
res.sort()
for i, x in enumerate(res):
    # print(i, x)
    if i==q:
        ans = str(x)
        print(ans + str(x)[-1]*p)
        exit()