#include <bits/stdc++.h>
using namespace std;
const int N=2e5+5,inf=2e9;
struct node{
    int l,r;
}qk[N];
int t,n,m,k,a,A[N],b[N],ans;
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+ch-'0';ch=getchar();}
    return x*f;
}
bool cmp(node a,node b){
    return a.l<b.l;
}
bool check(int x){
    priority_queue<int> q;
    while(q.size()) q.pop();
    for(int i=1;i<=n;i++) b[i]=A[i]-A[i-1];
    int now=1,res=0;
    for(int i=1;i<=n;i++){
	b[i]+=b[i-1];
	while(qk[now].l==i) q.push(qk[now++].r);
	while(q.top()>=i&&b[i]<x&&q.size()){
	    b[i]+=a;
	    b[q.top()+1]-=a;q.pop();
	    res++;
	}
	if(res>k||b[i]<x) return 0;
    }
    return 1;
}
int main(){
    t=read();
    while(t--){
	int l=inf,r=-inf;
	ans=-1;
	n=read();m=read();k=read();a=read();
	for(int i=1;i<=n;i++) A[i]=read(),l=min(l,A[i]),r=max(r,A[i]);
	for(int i=1;i<=m;i++){
	    qk[i].l=read();qk[i].r=read();
	}
	sort(qk+1,qk+1+m,cmp);
	r=l+a*m;
	while(l<=r){
	    int mid=(l+r)>>1;
	    if(check(mid)){
		l=mid+1;
		ans=mid;
	    }
	    else r=mid-1;
	}
	cout<<ans<<endl;
    }
    return 0;
}