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

using namespace std;

#define MAXN 200001

struct que{
	int f;
	int s;
	int inc;
	int lca;
	int odd;
};

int n,m,k;
int weight[MAXN];
int inc[MAXN];
int color[MAXN];
int postOrd[MAXN];
int depth[MAXN];
int prevvv[MAXN];
int sstime[MAXN];
vector <int> G[MAXN];
vector <que> quer;
vector <que> queries;
vector <int> roots;
int postOrdCount=0;
long long int allWaste=0;

bool queSorter(que a, que b){
	if(sstime[a.lca]==sstime[b.lca]){
			if(a.odd==b.odd){
					if(a.inc<b.inc){
						return true;
					}else{
						return false;
					}
			}else if(a.odd<b.odd){
				return true;
			}else{
				return false;
			}
	}else if(sstime[a.lca]<sstime[b.lca]){
		return true;
	}else{
		return false;
	}
}

void readIn(){
	scanf("%d%d%d",&n,&m,&k);
	for(int i=1;i<=n;++i){
		scanf("%d",&weight[i]);
	}
	int a,b;
	int t=0;
	for(int i=0;i<m;++i){
		scanf("%d%d",&a,&b);
		G[b].push_back(a);
		t++;
		sstime[a]=t;
		inc[a]++;
	}
	que el;
	for(int i=0;i<k;++i){
		scanf("%d%d",&el.f,&el.s);
		el.inc=i;
		quer.push_back(el);
	}
	for(int i=1;i<=n;++i){
		if(inc[i]==0){
			roots.push_back(i);
		}
	}
}

void dfs(int s, int col){
	for(int i=0;i<G[s].size();++i){
		int w=G[s][i];
		//printf("-> %d %d\n",s,w);
		depth[w]=depth[s]+1;
		color[w]=col;
		prevvv[w]=s;
		dfs(w,col);
	}
	postOrdCount++;
	postOrd[s]=postOrdCount;
}

void startDfs(){
	int coll=0;
	for(int i=0;i<roots.size();++i){
		coll++;
		color[roots[i]]=coll;
		depth[roots[i]]=0;
		prevvv[roots[i]]=-1;
		dfs(roots[i],coll);
	}
}

int getLca(int a, int b){
	while(depth[a]>depth[b]){
		a=prevvv[a];
	}
	while(depth[b]>depth[a]){
		b=prevvv[b];
	}
	while(a!=b){
		a=prevvv[a];
		b=prevvv[b];
	}
	return a;
}

void filterQueries(){
	que qq;
	for(int i=0;i<quer.size();++i){
		if(color[quer[i].f]==color[quer[i].s]){
			qq=quer[i];
			qq.lca=getLca(qq.f,qq.s);
			qq.odd=max(depth[qq.f],depth[qq.s])-depth[qq.lca];
			queries.push_back(qq);
		}
	}
}

void runMain(){
	sort(queries.begin(),queries.end(),queSorter);
	int waste;
	for(int i=0;i<queries.size();++i){
		waste=min(weight[queries[i].f],weight[queries[i].s]);
		weight[queries[i].f]-=waste;
		weight[queries[i].s]-=waste;
		allWaste+=2*waste;
	}
}

int main(){
	readIn();
	startDfs();
	filterQueries();
	runMain();
	printf("%lld\n",allWaste);
	return 0;
}