I. Starry Night
time limit per test
10 seconds
memory limit per test
1024 megabytes
input
standard input
output
standard output
Examples
Input
1 4
0 0
-1 -1
-1 1
1 1
1 -1
Output
1.414214
Input
2 2
-1 -1
1 1
-2 2
2 -2
Output
2.828427
Input
3 3
0 0
1 1
0 2
-100000000 -100000000
-99999999 -99999999
-100000000 -99999998
Output
0.000000
Input
5 20
401 -924
-804 641
-659 -864
239 -295
-329 883
873 788
613 627
770 124
-152 -49
697 -123
161 -104
701 63
-343 146
122 656
-99 -710
-156 -197
-869 -152
-414 -699
-599 -709
-365 -568
420 883
353 919
546 901
485 30
672 -575
Output
575.692976