// pozwoliłem sobie pożyczyć kod na LCA z topcodera
// http://community.topcoder.com/tc?module=Static&d1=tutorials&d2=lowestCommonAncestor#Another%20easy%20solution%20in%20O%28N%20logN,%20O%28logN%29
//

#include <list>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <cstdio>
#include <queue>

#define max(a,b) (((a)>(b))?(a):(b))
#define min(a,b) (((a)<(b))?(a):(b))

using namespace std;

int ILE[200005];
int T[200005];
vector<int> R1;
vector<int> R2;
long long int WYNIK;
int N, M, K;

vector<int> FOO[200005];

vector<int> start;

int a,b;

int vis[200005];
int nrk[200005];
int L[200005];


vector<int> sas[200005];

queue<int> bbq;

int tablica[200005][20];
int TABLICA[200005][20];

void BFS(int st)
{
	vis[st] = st;
	L[st] = 0;
	
	bbq.push(st);
	while(!bbq.empty())
	{
		int u = bbq.front();
		bbq.pop();
		vis[u] = st;
		for (int i = 0;i<sas[u].size();++i)
		{
			L[sas[u][i]]=L[u]+1;
			bbq.push(sas[u][i]);
		}
	}
}

int query(int p,int q)
{
	int tmp, log, i;
	if ( L[p] < L[q] )
	{
		tmp = p;
		p = q;
		q = tmp;
	}
	for (log = 1; (1<<log) <= L[p]; ++log);
	--log;

	int nk=0;
	for (i = log; i >=0;--i)
		if ( L[p] -  (1<<i) >= L[q])
		{
			nk = TABLICA[p][i];
			p = tablica[p][i];
		}
	if (p==q) 
		return nk; //L[q];

	for ( i = log; i>=0; --i)
		if ( tablica[p][i] != -1 && tablica[p][i] != tablica[q][i])
		{
			p=tablica[p][i]; 
			q=tablica[q][i];
		}

	return max(nrk[p],nrk[q]);//L[T[p]];

	//if (p<q)
}

int main()
{
	scanf("%d %d %d", &N, &M, &K);
	for (int i = 1; i<=N;++i)
		scanf("%d",ILE+i);
	for (int i = 0; i<M;++i)
	{
		scanf("%d %d", &a, &b);
		T[a] = b;
		sas[b].push_back(a);
		nrk[a] = i;
	}

	for (int i =1;i<=N;++i)
	{
		if ( vis[i] ) continue;
		int u = i;
		while( T[u] != 0 )
			u = T[u];
		BFS(u);
	}


	for (int i = 1; i<=N;++i)
		for (int j = 0; (1<<j) < N; ++j )
			tablica[i][j] = -1;

	for (int i = 1; i<=N; ++i)
	{
		tablica[i][0] = T[i];
		TABLICA[i][0] = nrk[i];
	}
	for (int j = 1; (1<<j) < N; ++j)
		for (int i = 1; i<=N; ++i)
			if (tablica[i][j-1] != -1)
			{
				TABLICA[i][j] = TABLICA[tablica[i][j-1]][j-1];
				tablica[i][j] = tablica[tablica[i][j-1]][j-1];
			}

	for (int i = 0;i<K;++i)
	{
		int r1,r2;
		scanf("%d %d",&r1,&r2);
		if ( vis[r1] != vis[r2] )
			continue;

		int LL = query(r1,r2);
		FOO[LL].push_back( R1.size() );
		R1.push_back(r1);
		R2.push_back(r2);
	}

	for (int i = 0; i<=M;++i)
	{
		//while (!FOO[i].empty())
		for (int j = 0; j<FOO[i].size();++j)
		{
			//int ind = FOO[i].front();
			int ind = FOO[i][j];
			//FOO[i].pop();
			long long int m = min( ILE[R1[ind]],ILE[R2[ind]]);
			WYNIK += 2*m;
			ILE[R1[ind]] -= m;
			ILE[R2[ind]] -= m;
		}
	}
	printf("%lld",WYNIK);
	return 0;
}