# 2桁以上なら最初の桁と残りの桁が、12,13,14,,,19,23,24,25,,,,89

two_digit = []
for a in range(1, 10):
    for b in range(a+1, 10):
        two_digit.append((a, b))
L = len(two_digit)
        
#print(two_digit)
#print(L)

N = int(input())
b_num = (N-1)//L+1
idx = (N-1)%L
ans = str(two_digit[idx][0])+str(two_digit[idx][1])*b_num
print(ans)