D. Dreamoon and Sets
题目连接：
http://www.codeforces.com/contest/476/problem/D
Description
Dreamoon likes to play with sets, integers and . is defined as the largest positive integer that divides both a and b.
Let S be a set of exactly four distinct integers greater than 0. Define S to be of rank k if and only if for all pairs of distinct elements si, sj from S, .
Given k and n, Dreamoon wants to make up n sets of rank k using integers from 1 to m such that no integer is used in two different sets (of course you can leave some integers without use). Calculate the minimum m that makes it possible and print one possible solution.
Input
The single line of the input contains two space separated integers n, k (1 ≤ n ≤ 10 000, 1 ≤ k ≤ 100).
Output
On the first line print a single integer — the minimal possible m.
On each of the next n lines print four space separated integers representing the i-th set.
Neither the order of the sets nor the order of integers within a set is important. If there are multiple possible solutions with minimal m, print any one of them.
Sample Input
1 1
Sample Output
5
1 2 3 5
Hint
题意
让你构造n个集合，使得每个集合里面都有四个元素，且两两元素之间的gcd都是k
让你使得其中最大数最小
题解：
其实就是样例的构造方法，这个得自己手玩一玩才行
代码
#include<bits/stdc++.h>
using namespace std;
int main()
{
int n,k;
scanf("%d%d",&n,&k);
printf("%d
",(n-1)*k*6+5*k);
for(int i=0;i<n;i++)
printf("%d %d %d %d
",i*k*6+k,i*k*6+2*k,i*k*6+3*k,i*k*6+5*k);
}