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#include <cstdio>
#include <algorithm>
#include <vector>

#define MAXN 200003
#define MAXK 500003

typedef long long LL;
typedef std::vector<int> VI;

struct FindAndUnion
{
	int p[MAXN],r[MAXN];
	int F(int x);
	void U(int x,int y);
}FNU;

int n,m,k;
int g[MAXN],depth[MAXN];
int sub_size[MAXN];
bool pos_in_deg[MAXN];
bool finished[MAXN];
VI G[MAXN],ENQ[MAXN],roots;
int F[MAXN],P[MAXN],ANC[MAXN],Q[MAXN],rt[MAXN];
int c[MAXK],d[MAXK],order[MAXK];
int p_lvl[MAXK],p_edge[MAXK];
LL result;

void T(int root);
int sec(int x,int i);

int main()
{
	scanf("%d%d%d",&n,&m,&k);
	for(int i = 1; i <= n; ++i)
		scanf("%d",g+i),F[i] = -1;
	for(int i = 1,a,b; i <= m; ++i)
		scanf("%d%d",&a,&b),G[b].push_back(a),pos_in_deg[a] = 1;
	for(int i = 1; i <= n; ++i)
		if(!pos_in_deg[i])
			roots.push_back(i);
	for(int i = 1; i <= k; ++i)
		scanf("%d%d",c+i,d+i),ENQ[c[i]].push_back(i),ENQ[d[i]].push_back(i),order[i] = i,p_lvl[i] = p_edge[i] = -1;
	
	for(int i = 1; i <= n; ++i)
		std::reverse(G[i].begin(),G[i].end());
	
	for(int root : roots)
		T(root);
		
	std::sort(order+1,order+k+1,[&](int i,int j)->bool
	{
		if(p_lvl[i] == p_lvl[j])
		{
			if(p_edge[i] == p_edge[j]) return i < j;
			return p_edge[i] > p_edge[j];
		}
		return p_lvl[i] > p_lvl[j];
	});
	
	for(int i = 1,r_i; i <= k; ++i)
	{
		if(p_lvl[r_i = order[i]] == -1) continue;
		int x = std::min(g[c[r_i]],g[d[r_i]]);
		g[c[r_i]] -= x;
		g[d[r_i]] -= x;
		result += (LL)(x);
	}
	
	printf("%lld",result<<1);
	
	return 0;
}

void T(int root)
{
	int q,v,u;
	Q[q = 1] = root;
	ANC[root] = root;
	F[root] = G[root].size();
	P[root] = root;
	depth[root] = 0;
	rt[root] = root;
	while(q)
	{
		if(F[v = Q[q]])
		{
			u = G[v][--F[v]];
			Q[++q] = u;
			ANC[u] = u;
			F[u] = G[u].size();
			P[u] = v;
			depth[u] = depth[v] + 1;
			rt[u] = root;
		}
		else
		{
			for(int enq : ENQ[v])
				if(rt[v] == rt[u = sec(v,enq)])
				{
					if(finished[u])
					{
						p_lvl[enq] = depth[ANC[FNU.F(u)]];
						if(p_edge[enq] == -1)
							p_edge[enq] = F[ANC[FNU.F(u)]];
					}
					else
						p_edge[enq] = F[u];
				}
			FNU.U(P[v],v);
			ANC[FNU.F(v)] = P[v];
			finished[v] = 1;
			--q;
		}
	}
}

int FindAndUnion::F(int x)
{
	return p[x] == 0 ? x : p[x] = F(p[x]);
}

void FindAndUnion::U(int x,int y)
{
	x = F(x);
	y = F(y);
	if(r[x] > r[y])
		p[y] = x;
	else if(r[x] < r[y])
		p[x] = y;
	else if(x != y)
	{
		++r[x];
		p[y] = x;
	}
}

inline int sec(int x,int i)
{
	return x == c[i] ? d[i] : c[i];
}