# Problem D

Nafnatalning

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en
is
The baptism is coming up real soon, only $42$ days! They need to decide what they are going to name the twins before then. Every day they can look at $P$ pairs of names. They have asked you to figure out how many days it will take to look at all pairs of names.

## Input

The first line of the input contains two integers $2 \leq n \leq 10^6$ and $1 \leq P \leq 10^9$, in that order. Then there is a single line with $n$ integers, with the $i$-th integer being $0 \leq a_i \leq 1000$.

## Output

Print how many days it will take Sunna and Ari to take a look at all the names.

## Scoring

Group |
Points |
Constraints |

1 |
50 |
$2 \leq n \leq 10^3, 0 \leq a_i \leq 10$ |

2 |
50 |
No further constraints |

Sample Input 1 | Sample Output 1 |
---|---|

2 5 2 3 |
2 |

Sample Input 2 | Sample Output 2 |
---|---|

10 5 1 1 1 1 1 1 1 1 1 1 |
9 |