#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll INF = LLONG_MAX / 4;


int main(){
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    ll N, M, C;
    cin >> N >> M >> C;
    vector<vector<pair<ll, ll>>> g(N + 1);
    auto add_edge = [&](ll i, ll j, ll c) {
        g[i].emplace_back(j, c);
        g[j].emplace_back(i, c);
    };
    ll ans = 0;
    for(ll i = 0; i < N; i++) {
        ll A;
        cin >> A;
        add_edge(i, i + 1, A);
        ans += A;
    }
    while(M--) {
        ll L, R;
        cin >> L >> R;
        add_edge(--L, R, C);
    }
    auto dijkstra = [&](ll s) -> vector<ll> {
        vector cost(N + 1, LLONG_MAX);
        priority_queue q(greater<>{}, vector<pair<ll, ll>>{});
        auto push = [&](ll i, ll c) {
            if(cost[i] <= c) return;
            cost[i] = c;
            q.emplace(c, i);
        };
        push(s, 0);
        while(q.size()) {
            auto [c, i] = q.top();
            q.pop();
            // if(cost[i] != c) continue;
            for(auto [j, d] : g[i]) push(j, c + d);
        }
        return cost;
    };
    ans -= dijkstra(0)[N];
    cout << ans << endl;
}