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Barr the bear is bored. He grabs the nearest piece of paper and scribbles an equation:

*a*_{1} - *a*_{2} + *a*_{3} - *a*_{4} + ... + *a*_{N-1} - *a _{N}* =

*x*.

Naturally, *N* has to be even for the equation to hold. Then he takes his trusty random number generator and starts generating random integers. He records the first *K* such integers on a card, the next *K* integers on another card, and so on, until he has recorded *K***N* integers on *N* cards.

He decides to align the cards nicely with the variables, each card to 1 variable. Then he picks a number from each card to be the value of the respective variable in the equation. He wonders, how can he do this such that the value *x* is minimised?

He does not wonder for long. After 10 seconds, he realises, "This is trivial." Can you figure out his trivial solution?

## Input

The first line contains integers*N*(2 ≤

*N*≤ 75,000,

*N*is even) and

*K*(1 ≤

*K*≤ 100). The following

*N*lines contains

*K*space-separated integers each; the

*j*

^{th}integer of the

*i*

^{th}of these lines is an integer

*a*

_{i,j}that represents the

*j*

^{th}integer on the

*i*

^{th}card (1 ≤

*i*≤

*N*, 1 ≤

*j*≤

*K*, -2000 ≤

*a*

_{i,j}≤ 2000).

## Output

The first line should contain a single integer: the minimum possible*x*assuming that you align the cards and choose the numbers optimally.

## Sample Input 1

4 2 -2 3 -5 -3 3 6 -10 7

## Sample Output 1

-24

## Explanation for Sample Output 1

A possible optimal solution is to align the the 2nd card with*a*

_{1}, the 1st card with

*a*

_{2}, the 4th card with

*a*

_{3}and the 3rd card with

*a*

_{4}. Then pick integers -5, 3, -10, 6 respectively.

*x*= (-5) - 3 + (-10) - 6 = -24

### Tags

### Subtasks and Limits

Subtask | Score | #TC | Time | Memory | Scoring |
---|---|---|---|---|---|

1 | 0 | 1 | 3s | 32MB | Average |

2 | 100 | 15 | 3s | 32MB | Average |

### Judge Compile Command

g++ ans.cpp -o equation -Wall -static -O2 -lm -m64 -s -w -std=gnu++14 -fmax-errors=512