#include<iostream>
#include<stack>

using namespace std;

struct info
{
    int adjacent[10005],total,status;
}list[10005];

bool visited[10005];
stack<int>s;

bool possibile(int total);
bool check(int point);

int main()
{
    int friends,i,test,friendships,f1,f2;
    cin>>test;
    while(test--)
    {
        cin>>friends>>friendships;
        for(i=0;i<friends;i++)
        {
            list[i].total=visited[i]=false;
            cin>>list[i].status;
        }
        for(i=0;i<friendships;i++)
        {
            cin>>f1>>f2;
            list[f1].adjacent[list[f1].total++]=f2;
            list[f2].adjacent[list[f2].total++]=f1;
        }
        if(possibile(friends))
            cout<<"POSSIBLE"<<endl;
        else
            cout<<"IMPOSSIBLE"<<endl;
    }
    return 0;
}

bool possibile(int friends)
{
    int i,flag=0;
    while(!flag)
    {
        flag=1;
        for(i=0;i<friends;i++)
        {
            if(!visited[i])
            {
                flag=0;
                if(!check(i))
                    return false;
            }
        }
    }
    return true;
}

bool check(int point)
{
    int imbalance=0,temp,temp2,size,i;
    while(!s.empty())
        s.pop();
    s.push(point);
    while(!s.empty())
    {
        temp=s.top();
        s.pop();
        visited[temp]=true;
        imbalance+=list[temp].status;
        size=list[temp].total;
        for(i=0;i<size;i++)
        {
            temp2=list[temp].adjacent[i];
            if(visited[temp2]==false)
                s.push(temp2);
        }
    }
    return !imbalance;
}