#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL

int main(){
	
	int n,m,k;
	cin>>n>>m>>k;
	
	mcf_graph<int,long long> G(n*(k+1));
	rep(i,n){
		rep(j,k){
			G.add_edge(i*(k+1)+j,i*(k+1)+j+1,1,0);
		}
	}
	vector<long long> a(m),b(m),c(m);
	rep(i,m)cin>>c[i];
	rep(i,m){
		cin>>a[i]>>b[i];
		a[i]--,b[i]--;
	}
	rep(i,m){
		rep(_,2){
			rep(j,k+1){
				G.add_edge(a[i]*(k+1)+j,b[i]*(k+1)+j,1,c[i]);
				if(j!=k){
					G.add_edge(a[i]*(k+1)+j,b[i]*(k+1)+j+1,1,0);
				}
			}
			swap(a[i],b[i]);
		}
	}
	auto ans = G.flow(0,n*(k+1)-1,1);
	if(ans.first==0)cout<<-1<<endl;
	else cout<<ans.second<<endl;
	return 0;
}