Codeforces Round #460 (Div. 2)-B. Perfect Number

B. Perfect Number

time limit per test2 seconds
memory limit per test256 megabytes

Problem Description

We consider a positive integer perfect, if and only if the sum of its digits is exactly 10. Given a positive integer k, your task is to find the k-th smallest perfect positive integer.

Input

A single line with a positive integer k (1 ≤ k ≤ 10 000).

Output

A single number, denoting the k-th smallest perfect integer.

Examples

input
1
output
19

input
2
output
28

Note

The first perfect integer is 19 and the second one is 28.

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解题心得：

1. 题意是问你第n个所有位数之和加在一起为10的数是多少，刚开始也不知道数据范围，写了一个暴力程序跑了一下极限数据，极限数据也就1e7 多一点，时间给了2s，暴力轻松过。

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#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e4+100;
long long num[maxn],tot = 0;

long long get_sum(int x)
{
    int sum = 0;
    while(x)
    {
        int temp = x%10;
        sum += temp;
        x /= 10;
    }
    return sum;
}

int main()
{
    int n;
    scanf("%d",&n);
    for(long long i=19;;i++)
    {
        long long sum = get_sum(i);
        if(sum == 10)
        {
            tot++;
            if(tot == n)
            {
                printf("%lld",i);
                break;
            }
        }
    }
    return 0;
}