100 atcoder#ABC106C. [ABC106C] To Infinity
[ABC106C] To Infinity
Score: points
Problem Statement
Mr. Infinity has a string consisting of digits from 1
to 9
. Each time the date changes, this string changes as follows:
- Each occurrence of
2
in is replaced with22
. Similarly, each3
becomes333
,4
becomes4444
,5
becomes55555
,6
becomes666666
,7
becomes7777777
,8
becomes88888888
and9
becomes999999999
.1
remains as1
.
For example, if 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 days. What is the -th character from the left in the string after days?
Constraints
- is a string of length between and (inclusive).
- is an integer between and (inclusive).
- The length of the string after days is at least .
Input
Input is given from Standard Input in the following format:
Output
Print the -th character from the left in Mr. Infinity's string after days.
1214
4
2
The string 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 days is 12222
. As , we should print the fourth character, 2
.
3
157
3
The initial string is 3
. The string after days consists only of 3
.
299792458
9460730472580800
2