#include<iostream>
#include<iomanip>
#include<vector>
#include<math.h>
#include<algorithm>
#include<map>
#include<queue>
#include<stack>
#include<deque>
#include<set>
#include<cmath>
#include<ctime>
#include<bitset>
#define rep(i,a,b) for(int i=a;i<=b;i++)
using namespace std;
using ll = long long;
using vec = vector<ll>;
using Graph = vector<vec>;
using Pair = pair<ll,ll>;

void debug1(vec v){for(auto x:v)cout << x << ' ';cout << endl;}
void debug2(vector<Pair> v){for(auto x:v)cout << '(' << x.first << ',' << x.second << ')' << endl;}
void debug3(Graph v){rep(i,0,v.size()-1)debug1(v[i]);cout << endl;}
ll st = 1000000000000009;
set<Pair>visited;
Graph dist(100009,vec(4,st));
int n,m,k;
set<pair<ll,Pair>>s;
vector<vector<Pair>>g(100009);
void dij(){
    Pair p = s.begin()->second;
    visited.insert(p);
    ll now = p.first;
    ll cou = p.second;
    ll d = dist[now][cou];
    for(auto next:g[now]){
        if(dist[next.second][cou] > d + next.first){
            s.insert({d + next.first,{next.second,cou}});
            dist[next.second][cou] = d + next.first;
        }
        if(cou < 3 && dist[next.second][cou+1] > d){
            s.insert({d,{next.second,cou+1}});
            dist[next.second][cou+1] = d;
        }
    }
    while(!s.empty() && visited.count(s.begin()->second)){
        s.erase(s.begin());
    }

    if(!s.empty())dij();
}
int main(){
    cin >> n >> m >> k;
    
    vec c(m+1);
    rep(i,1,m)cin >> c[i];
    rep(i,1,m){
        int u,v;
        cin >> u >> v;
        g[u].push_back({c[i],v});
        g[v].push_back({c[i],u});
    }
    dist[1][0] = 0;
    s.insert({0,{1,0}});
    dij();
    ll ans = st;
    rep(i,0,k)ans = min(ans, dist[n][i]);
    
    if(ans < st)cout << ans << endl;
    else cout << -1 << endl;
    //rep(i,1,n)cout << dist[i][0] << " ";
}