网址：http://codeforces.com/gym/101911/problem/D

备注：因自己写了出来，难度不大，涉及范围在标题指出，故不做分析。

#include<bits/stdc++.h>
using namespace std;
const int MAX_N = 2e5+50;
struct NUM;
typedef map<int,NUM> MAP;
MAP M;
struct ANS
{
    int a,b;
}ans[MAX_N];
struct NUM
{
    int num;
    int cnt;
    int pos;
    vector<int> factor;
};
int a[MAX_N];
void build(int n,vector<int>&vec,int &cnt)
{
    int k = sqrt(n*1.00);
    for(int i=1;i<=k;i++){
        if(n%i==0){
            vec.push_back(i);
            vec.push_back(n/i);
            vec.push_back(n/i);
            vec.push_back(i);
            cnt+=4;
        }
    }
    if(vec[vec.size()-1]==vec[vec.size()-2]){
        vec.erase(vec.end()-1);vec.erase(vec.end()-1);cnt-=2;
    }
}

int main()
{
    //ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++){
        int num;
        scanf("%d",&num);
        a[i] = num;
        if(!M.count(num)){
            vector<int>buf;
            int cnt = 0;
            build(num,buf,cnt);
            NUM xx;xx.cnt = cnt,xx.num=0,xx.factor=buf,xx.pos=0;
            M[num] = xx;
        }
        M[num].num++;
    }
    bool flag1 = 1;
    for(int i=0;i<n&&flag1;i++){
        if(M[a[i]].num){
            M[a[i]].num--;
            if(M[a[i]].pos==M[a[i]].cnt){
                flag1 = 0;
                break;
            }
            ans[i].a = M[a[i]].factor[M[a[i]].pos];
            ans[i].b = M[a[i]].factor[M[a[i]].pos+1];
            M[a[i]].pos+=2;
        }
    }
    if(flag1){
        printf("YES\n");
        for(int i=0;i<n;i++){
            printf("%d %d\n",ans[i].a,ans[i].b);
        }
    }
    else{
        printf("NO\n");
    }
    return 0;
}