#include<bits/stdc++.h>
using namespace std;
const int N=2e5+5;
using ll=long long;
const ll inf=1e18;
int c,T,n,m,a[N];
ll sum,dis[N];
bool vis[N];
vector<pair<int,int>>e[N];
struct node{
	int id;ll d;
	bool operator<(const node &b)const{return d>b.d;}
}tmp;
priority_queue<node>pq;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0),cout.tie(0);
//	freopen("card.in","r",stdin);
//	freopen("card.out","w",stdout);
	T=1;
	while(T--)
	{
		cin>>n>>m>>c,sum=0;
		for(int i=1;i<=n;i++)cin>>a[i],sum+=a[i];
		for(int i=0;i<=n;i++)e[i].clear(),dis[i]=inf,vis[i]=0;
		for(int i=1;i<=n;i++)
		{
			e[i-1].emplace_back(i,a[i]);
			e[i].emplace_back(i-1,a[i]);
		}
		for(int i=1;i<=m;i++)
		{
			int l,r,w=c;
			cin>>l>>r;
			e[l-1].emplace_back(r,w);
			e[r].emplace_back(l-1,w);
		}
		dis[0]=0,pq.emplace((node){0,0});
		while(!pq.empty())
		{
			tmp=pq.top();pq.pop();
			int x=tmp.id;
			if(vis[x])continue;
			vis[x]=1;
			for(auto y:e[x])if(dis[x]+y.second<dis[y.first])
			{
				dis[y.first]=dis[x]+y.second;
				pq.emplace((node){y.first,dis[y.first]});
			}
		}
		cout<<sum-dis[n]<<'\n';
	}
	return 0;
}