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#include <iostream>
#include <vector>
#include <cstdio>

#define ST first
#define ND second
#define MP make_pair
#define PB push_back

using namespace std;

const int N = 200010;

vector<int> graf[N];
vector<pair<int, int> > pary[N];
int f[N][20], sp[N], ile[N], t1[N], t2[N], czas;
bool korzen[N];
long long int res;
int n, m, k, a, b;

void dfs(int v) {
	t1[v] = czas++;
	for (int i=0; i<graf[v].size(); i++) {
		f[graf[v][i]][0] = v;
		sp[graf[v][i]] = sp[v];
		dfs(graf[v][i]);
	}
	t2[v] = czas++;
}

void dfs2(int v) {
	for (int i=0; i<graf[v].size(); i++) {
		dfs2(graf[v][i]);
	}
	for (int i=0; i<pary[v].size(); i++) {
		int a = pary[v][i].ST;
		int b = pary[v][i].ND;
		int mi = min(ile[a], ile[b]);
		res += mi;
		ile[a] -= mi;
		ile[b] -= mi;
	}
}

bool czy_potomek(int a, int b) { // czy a nad b
	return t1[a] <= t1[b] && t2[a] >= t2[b];
}

int lca(int a, int b) {
	int skok = 18;
	if (czy_potomek(a, b)) {
		return a;
	}
	if (czy_potomek(b, a)) {
		return b;
	}
	while (skok >= 0) {
		if (czy_potomek(f[a][skok], b)) {
			skok--;
		} else {
			a = f[a][skok];
		}
	}
	return f[a][0];
}

int main() {
	scanf("%d %d %d", &n, &m, &k);
	for (int i=1; i<=n; i++) {
		scanf("%d", &ile[i]);
		korzen[i] = true;
	}
	for (int i=1; i<=m; i++) {
		scanf("%d %d", &a, &b);
		graf[b].PB(a);
		korzen[a] = false;
	}
	for (int i=1; i<=n; i++) {
		if (korzen[i]) {
			f[i][0] = i;
			sp[i] = i;
			dfs(i);
		}
	}
	for (int i=1; i<=18; i++) {
		for (int j=1; j<=n; j++) {
			f[j][i] = f[f[j][i-1]][i-1];
		}
	}
	for (int i=1; i<=k; i++) {
		scanf("%d %d", &a, &b);
		if (sp[a] == sp[b]) {
			int u = lca(a, b);
			pary[u].PB(MP(a, b));
		}
	}
	for (int i=1; i<=n; i++) {
		if (korzen[i]) {
			dfs2(i);
		}
	}
	printf("%lld\n", res * 2);
	return 0;
}