D. Golf
time limit per test
1 second
memory limit per test
1024 megabytes
input
standard input
output
standard output
Examples
Input
10 1 7
2 4
8 8
1 3
Output
2.333333
Input
10 1 7
2 5
8 11
1 3
Output
3.166667
Input
10 10 0
2 4
1 2
2 2
Output
4.000000