#include<bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define mp make_pair
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
template<typename T,typename U>
T ceil(T x, U y) {return (x>0?(x+y-1)/y:x/y);}
template<typename T,typename U>
T floor(T x, U y) {return (x>0?x/y:(x-y+1)/y);}
template<class T,class S>
bool chmax(T &a,const S b) {return (a<b?a=b,1:0);}
template<class T,class S>
bool chmin(T &a,const S b) {return (a>b?a=b,1:0);}
int popcnt(int x) {return __builtin_popcount(x);}
int popcnt(ll x) {return __builtin_popcountll(x);}
int topbit(int x) {return (x==0?-1:31-__builtin_clz(x));}
int topbit(ll x) {return (x==0?-1:63-__builtin_clzll(x));}
int lowbit(int x) {return (x==0?-1:__builtin_ctz(x));}
int lowbit(ll x) {return (x==0?-1:__builtin_ctzll(x));}

#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define ac 1
#define wa 0
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

#define int long long
const int N=2e5+9,inf=2e18;
int n,m,d[N],ans,c;
vp e[N];

void dijkstra() {
  d[1]=0; rep(i,2,n+1) d[i]=inf;
  priority_queue<pii>q; q.push(pii(0,1));
  while(!q.empty()) {
    int u=q.top().se; q.pop();
    for(auto [v,w]:e[u]) if(d[v]>d[u]+w)
      d[v]=d[u]+w, q.push(pii(-d[v],v));
  }
}

signed main() {
  n=read(), m=read(), c=read();
  rep(i,1,n) {
    int a=read(); ans+=a;
    e[i].eb(i+1,a), e[i+1].eb(i,a);
  }
  rep(i,1,m) {
    int l=read(), r=read();
    e[l].eb(r+1,c), e[r+1].eb(l,c);
  }
  dijkstra();
  printf("%lld\n",ans-d[n+1]);
  return 0;
}