Problem:
﻿Score: 300 points

Problem Statement

Mr. Infinity has a string S consisting of digits from 1 to 9. Each time the date changes, this string changes as follows:

Each occurrence of 2 in S is replaced with 22. Similarly, each 3 becomes 333, 4 becomes 4444, 5 becomes 55555, 6 becomes 666666, 7 becomes 7777777, 8 becomes 88888888 and 9 becomes 999999999. 1 remains as 1.

For example, if S is 1324, it becomes 1333224444 the next day, and it becomes 133333333322224444444444444444 the day after next.
You are interested in what the string looks like after 5 \times 10^{15} days. What is the K-th character from the left in the string after 5 \times 10^{15} days?

Constraints

S is a string of length between 1 and 100 (inclusive).

K is an integer between 1 and 10^{18} (inclusive).

The length of the string after 5 \times 10^{15} days is at least K.

Input

Input is given from Standard Input in the following format:

S
K

Output

Print the K-th character from the left in Mr. Infinity's string after 5 \times 10^{15} days.

Sample Input 1

1214
4

Sample Output 1

2

The string S changes as follows:

Now: 1214

After one day: 12214444

After two days: 1222214444444444444444

After three days: 12222222214444444444444444444444444444444444444444444444444444444444444444

The first five characters in the string after 5 \times 10^{15} days is 12222. As K=4, we should print the fourth character, 2.

Sample Input 2

3
157

Sample Output 2

3

The initial string is 3. The string after 5 \times 10^{15} days consists only of 3.

Sample Input 3

299792458
9460730472580800

Sample Output 3

2

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections.Generic;
namespace Collections
{
	class program
	{
    //static long MAX_LONG = 5000000000000000;
		static void Main(string[] args)
		{
			// 入力
      string S = Console.ReadLine();
      long K = long.Parse(Console.ReadLine());
			//int N = Int32.Parse(Console.ReadLine());
			//string[] input = Console.ReadLine().Split(' ');
      // 要素数１〜Nの部分数列を取得する

      int num = 0;
      for(int i = 0; i<S.Length; i++)
      {
        if(S[i] == '1')
        {
          num++;
        }
        else
        {
          Console.WriteLine(S[i]); //2以降は５０００兆日後かならずKを超える
          return;
        }
        if(num >= K)
        {
          Console.WriteLine(S[i]); // 1だけで超えるかもしれない
          return;
        }
      }
    }
	}
}