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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"bufio"
	"os"
	"strconv"
	"fmt"
)


type Scanner struct {
	innerScanner *bufio.Scanner
}

func NewScanner() *Scanner {
	sc := new(Scanner)
	innerScanner := bufio.NewScanner(os.Stdin)
	innerScanner.Split(bufio.ScanWords)
	sc.innerScanner = innerScanner
	return sc
}

func (sc Scanner) scan() {
	sc.innerScanner.Scan()
}

func (sc Scanner) next() string {
	sc.scan()
	return sc.innerScanner.Text()
}

func (sc Scanner) nextInt() int {
	i, _ := strconv.Atoi(sc.next())
	return i
}

func (sc Scanner) nextFloat() float64 {
	f, _ := strconv.ParseFloat(sc.next(), 64)
	return f
}
func main() {
	sc := NewScanner()
	s := sc.next()
	k := sc.nextInt() - 1
	for i := 0; i < len(s); i++ {
		if s[i] == '1' {
			if i == k {
				fmt.Println(string(s[i]))
				break
			}
		} else {
			fmt.Println(string(s[i]))
			break
		}
	}
}