hoj 13926 Floppy Music

//手动memset就wa了
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <cmath>
#include <cstdlib>
#include <ctime>
using namespace std;
typedef long long LL;
const int maxn=(int)1e4 +10;
int a[105][maxn];
int main()
{
#ifdef shuaishuai
    freopen("C:\Users\hasee\Desktop\a.txt","r",stdin);
    //freopen("C:\Users\hasee\Desktop\b.txt","w",stdout);
#endif
    int T;
    int t,n;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d",&t,&n);
        memset(a,0,sizeof a);
        for(int i=0; i<=t; i++) a[0][i]=1;
        int x,y;
        for(int i=1; i<=n; i++)
        {
            scanf("%d%d",&x,&y);
            int len=y-x;
            for(int j=0; j<=t; j++)
            {
                if(j-len>=0) a[i][j]|=a[i-1][j-len];
                if(j+len<=t) a[i][j]|=a[i-1][j+len];
            }
        }
//            for(int i=0;i<=n;i++){
//                for(int j=0;j<=t;j++)printf("%d ",a[i][j]);printf("
");
//            }
        int flag=0;
        for(int i=0; i<=t; i++)
        {
            flag|=a[n][i];
        }
        if(!flag)
        {
            printf("impossible
");
            return 0;
        }
    }
    printf("possible
");
    return 0;
}