res=[]
for i in range(1,10):
    for j in range(i+1,10):
        res.append(10*i+j)

N=int(input())
N-=1
A=N//36
B=N%36
a,b=res[B]//10,res[B]%10
print(a,end="")
for i in range(A+1):
    print(b,end="")
print()