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#include <cstdio>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <cassert>
#include <limits.h>

using namespace std;

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

typedef long long LL;
typedef long double LD;

typedef vector<int> VI;
typedef pair<int,int> PII;
#define REP(i,n) for(int i=0;i<(n);i++)
#define FOR(i,a,b) for(VAR(i,a);i<=(b);++i)
#define FORD(i,a,b) for(VAR(i,a);i>=(b);--i)
#define FORE(a,b) for(VAR(a,(b).begin());a!=(b).end();++a)
#define VAR(a,b) __typeof(b) a=(b)
#define SIZE(a) ((int)((a).size()))
#define ALL(x) (x).begin(),(x).end()
#define CLR(x,a) memset(x,a,sizeof(x))
#define ZERO(x) memset(x,0,sizeof(x))
#define S(t,i) scanf("%" ## t, &i)
#define SI(i) scanf("%d", &i)

//#define DEBUG

const int INF=INT_MAX;
const int MAXN=200000+5000;
const int MAXK=500000+5;

int n, m, k;

struct node;

struct substance{
    int g;
    
    int last;
    int next;
    int weight;
    
    int list_id;
    
    node* root;
    int pos;
};
substance ss[MAXN];

struct edge {
    int c,d;
    int step;
    int i;
};
edge reaction[MAXK];
int edgei;

int cmpEdges (const void * a, const void * b)
{
    edge *e1=(edge*)a;
        edge *e2=(edge*)b;
    
    if (e1->step!=e2->step) {
        return e1->step-e2->step;
    }
    return e1->i-e2->i;
}

void joinLists(int t, int f, int w){
    int lastt, lastf;
    lastt=ss[t].last;
    lastf=ss[f].last;
    
    ss[lastt].next=f;
    ss[lastt].weight=w;
    
    ss[t].last=lastf;
    ss[f].last=0; // empty
}

struct node {
    int left, right;
    node *ln;
    node *rn;
//    node *up;
    
    int maxVal;
};

//node nodes[4*MAXN];
int nodesi;
node *getNode() {
    //    return &nodes[nodesi++];
    return new node;
}

node basenodes[MAXN];

node *buildTree(int li, int ri){
    node *root;

#ifdef DEBUG
    assert(li!=ri);
#endif
    
    if (li+1==ri) {
        root=&basenodes[li];
        root->left=li;
        root->right=ri;
        
        root->ln=root->rn=0;
    } else {
        root=getNode();
        root->left=li;
        root->right=ri;
        
        int half=(li+ri)/2;
        root->ln=buildTree(li, half);
        root->rn=buildTree(half, ri);
        
        root->maxVal=max(root->ln->maxVal,root->rn->maxVal);
    }
    return root;
}

int getMaxVal(node *root, int li, int ri) {
    if (root->left>=li && root->right<=ri) {
        return root->maxVal;
    }

#ifdef DEBUG
    assert(li<root->right && ri>root->left);
#endif

    int maxVal=-1;
    
    int half=(root->left+root->right)/2;
    
    if (li<half) {
        int branchMax=getMaxVal(root->ln, li, ri);
        if (maxVal<branchMax) {
            maxVal=branchMax;
        }
    }
    if (ri>half) {
        int branchMax=getMaxVal(root->rn, li, ri);
        if (maxVal<branchMax) {
            maxVal=branchMax;
        }
    }
    
#ifdef DEBUG
    assert(maxVal>-1);
#endif
    
    return maxVal;
}


int main() {
    //ios_base::sync_with_stdio(0);
    
    SI(n);
    SI(m);
    SI(k);
    
    FOR(i,1,n) {
        SI(ss[i].g);
        ss[i].last=i;
    }
    REP(i, m) {
        int t,f;
        SI(f);
        SI(t);
        joinLists(t,f,i);
    }
    
    int bnodes_count=0;
    
    FOR(i, 1, n) {
        if (ss[i].last!=0) {
            
#ifdef DEBUG
            assert(ss[i].list_id==0);
#endif
            
            int firstNode=bnodes_count;
            ss[i].list_id=i;
            int ii=i;
            while (ss[ii].next) {
                basenodes[bnodes_count].maxVal=ss[ii].weight;
                bnodes_count++;
                
                ii=ss[ii].next;
                ss[ii].pos=bnodes_count;
                
#ifdef DEBUG
                assert(ss[ii].list_id==0);
#endif
                
                ss[ii].list_id=i;
    
            }
            if (firstNode<bnodes_count) {
                ss[i].pos=firstNode;
                ss[i].root=buildTree(firstNode, bnodes_count);
            }
        }
    }
    
    edgei=0; // first free
    REP(i, k) {
        int c,d;
        SI(c);
        SI(d);
        
        if (ss[c].list_id==ss[d].list_id) {
            edge &r=reaction[edgei];
            edgei++;
            
            r.c=c;
            r.d=d;
            r.i=i;
            
            node *root=ss[ss[c].list_id].root;
#ifdef DEBUG
         assert(root);
#endif

            if (ss[c].pos<ss[d].pos) {
                r.step=getMaxVal(root,ss[c].pos,ss[d].pos);
            } else {
                r.step=getMaxVal(root,ss[d].pos,ss[c].pos);
            }
            
        }
    }
    
    
    qsort(reaction, edgei, sizeof(edge), cmpEdges);

    LL residue=0;
    REP(i, edgei) {
        edge &r=reaction[i];
        LL q=min(ss[r.c].g,ss[r.d].g);
        ss[r.c].g-=q;
        ss[r.d].g-=q;
        residue+=2*q;
    }
    
    printf("%lld\n",residue);
    
    
	return 0;
}