#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <cmath>
#include <climits>
#include <algorithm>
#include <map>
#include <stack>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <utility>
#include <iomanip>

using namespace std;
typedef long long int ll;
ll pw(ll a, ll b, ll m){
	ll ans=1;
	while(b>0){
		if(b&1) ans=(ans*a)%m;
		a=(a*a)%m;
		b>>=1;
	}
	return ans;
}

ll gcd(ll a,ll b){
	if(a==0) return b;
	return gcd(b % a , a);
}

bool comp(const pair<int,int> &a,const pair<int,int> &b){
    return a.second>b.second;
}

ll n,m;
set<ll> has;
vector<ll> input;

void solve(ll l,ll r){
	ll sum=0;
	for(ll i=l;i<r+1;i++){
		sum+=input[i];
	}
	has.insert(sum);
	ll mid=(input[l]+input[r])/2;
	ll pos=-1;
	for(ll i=l;i<r+1;i++){
		if(input[i]<=mid){
			pos=i;
		}
		else{
			break;
		}
	}
	if(pos==-1 || pos==r) return;
	solve(l,pos);
	solve(pos+1,r);
}
void randomevent(){
	ll right=n;
	while(right>=0 && input[right-1]==right){
		right--;
	}
	double f=(right>0) ? 1:0;
	for(ll i=0;i<m;i++){
		ll r;cin>>r;
		double p;cin>>p;
		if(r>=right){
			f*=(1-p);
		}
	}
	cout<<fixed<<setprecision(12)<<(1-f)<<endl;
}



int main(){
#ifndef ONLINE_JUDGE
    freopen("input.txt","r", stdin);
    freopen("output.txt","w", stdout);
#endif 

    int t;cin>>t;
    while(t--){
    	cin>>n>>m;
    	for(ll i=0;i<n;i++){
    		ll p;cin>>p;
    		input.push_back(p);
    	}
    	randomevent();
    	input.clear();

    }
}