Score: $300$ points
Mr. Infinity has a string $S$ consisting of digits from 1
to 9
. Each time the date changes, this string changes as follows:
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?
Input is given from Standard Input in the following format:
$S$ $K$
Print the $K$-th character from the left in Mr. Infinity's string after $5 \times 10^{15}$ days.
1214 4
2
The string $S$ changes as follows:
1214
12214444
1222214444444444444444
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
.
3 157
3
The initial string is 3
. The string after $5 \times 10^{15}$ days consists only of 3
.
299792458 9460730472580800
2