#include<bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;

#define all(v) v.begin(),v.end()
using ll = long long;
using ull = unsigned long long;
using lll = __int128;
using vll=vector<ll>;
using vvll = vector<vector<ll>>;
using P = pair<ll,ll>;
using vp=vector<pair<ll, ll>>;
//using mint=modint1000000007;
//using mint=modint998244353;

const ll INF=1ll<<60;
ll mod10=1e9+7;
ll mod99=998244353;
const double PI = acos(-1);

#define rep(i,n) for (ll i=0;i<n;++i)
#define per(i,n) for(ll i=n-1;i>=0;--i)
#define rep2(i,a,n) for (ll i=a;i<n;++i)
#define per2(i,a,n) for (ll i=a;i>=n;--i)

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }

bool solve(){
    ll N,M,K;cin>>N>>M>>K;
    vll C(M);rep(i,M) cin>>C[i];
    vector<vp> ab(N);
    rep(i,M){
        ll a,b,c;cin>>a>>b;
        a--;b--;
        ab[b].push_back({C[i],a});
        ab[a].push_back({C[i],b});
    }

    vvll dp(N,vll(10,INF));
    using PP=pair<ll,P>;
    priority_queue<PP,vector<PP>,greater<PP>> pq;
    pq.push({0,{0,0}});
    dp[0][0]=0;
    while(pq.size()){
        auto [c,now]=pq.top();pq.pop();
        auto [n,cnt]=now;
        if(dp[n][cnt]<c) continue;
        for(auto [c2,to]:ab[n]){
            if(chmin(dp[to][cnt],c+c2)){
                pq.push({dp[to][cnt],{to,cnt}});
            }
            if(cnt>=5) continue;
            if(chmin(dp[to][cnt+1],c)){
                pq.push({dp[to][cnt+1],{to,cnt+1}});
            }
        }
    }
    ll ans=INF;
    rep(i,K+1) chmin(ans,dp[N-1][i]);
    cout << (ans==INF?-1:ans) << endl;
    return 0;
}



int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll T=1;//cin>>T;
    rep(i,T) solve();
}