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/*
 * LCA adapted from: http://www.topcoder.com/tc?d1=tutorials&d2=lowestCommonAncestor&module=Static
 */

#include <vector>
#include <list>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <string>

#define FOR(i,a,b)  for(int i=(a);i<(b);++i)
#define FORD(i,a,b) for(int i=(a);i>=(b);--i)
#define REP(i,a)    FOR(i,0,a)
#define MP          make_pair
#define PB          push_back
#define ST          first
#define ND          second

using namespace std;

typedef vector<int>             VI;
typedef vector<VI>              VVI;
typedef pair<int, int>          PII;
typedef vector<PII>             VII;
typedef long long int           LL;
typedef unsigned long long int  ULL;

const int MAXN = 200005;
const int MAXT = 2 * MAXN;
const int MAXLOGT = 19;
const int MAXK = 500005;

int n, m, k;
LL result;
int w[MAXN];
PII r[MAXK];
VII sorted[MAXN];

struct Node {
    Node() : left(0), right(0), parent(0) {}
    int left, right, parent;
};

Node tree[MAXT];
int T;
int pos[MAXN];
int depth[MAXT];

int dp[MAXT][MAXLOGT];

void fillTree() {
    T = 2 * n - 1;
    if (m == n - 1) return;

    int idx = 1;
    while (idx <= n+m && tree[idx].parent != 0) {
        ++idx;
    }
    tree[idx].parent = n+m+1;
    tree[n+m+1].left = idx;
    int free = n+m+1;

    while (free < 2 * n) {
        if (tree[idx].parent == 0) {
            tree[idx].parent = free;
            tree[free].right = idx;
            if (free < T) {
                tree[free+1].left = free;
                tree[free].parent = free+1;
            }
            ++free;
        }
        ++idx;
    }
}

void DFS(int v, int d) {
    depth[v] = d;
    if (tree[v].left != 0) DFS(tree[v].left, d+1);
    if (tree[v].right != 0) DFS(tree[v].right, d+1);
}

void initLCA() {
    FOR (i, 1, T) {
        for (int j = 0; (1 << j) <= T; ++j) {
            dp[i][j] = -1;
        }
    }

    FOR (i, 1, T) {
        dp[i][0] = tree[i].parent;
    }

    for (int j = 1; (1 << j) <= T; j++) {
        FOR (i, 1, T) {
            if (dp[i][j-1] != -1) {
                dp[i][j] = dp[dp[i][j-1]][j-1];
            }
        }
    }
}

int LCA(int p, int q) {
    int log;

    if (depth[p] < depth[q]) {
        swap(p, q);
    }

    for (log = 1; (1 << log) <= depth[p]; ++log);
    --log;

    FORD (i, log, 0) {
        if (depth[p] - (1 << i) >= depth[q]) {
            p = dp[p][i];
        }
    }

    if (p == q) {
        return p;
    }

    FORD (i, log, 0) {
        if (dp[p][i] != -1 && dp[p][i] != dp[q][i]) {
            p = dp[p][i];
            q = dp[q][i];
        }
    }

    return tree[p].parent;
}

void findTimes() {
    REP (i, k) {
        int time = LCA(r[i].ST, r[i].ND);
        if (time <= n + m) {
            sorted[time-n-1].PB(r[i]);
        }
    }
}

void simulate() {
    int change;
    REP (i, m) {
        for (auto re : sorted[i]) {
            change = min(w[re.ST], w[re.ND]);
            result += 2 * change;
            w[re.ST] -= change;
            w[re.ND] -= change;
        }
    }
}

int main() {
    scanf("%d %d %d", &n, &m, &k);
    REP (i, n) {
        scanf("%d", &w[i+1]);
        pos[i+1] = i+1;
    }
    int from, to;
    REP (i, m) {
        scanf("%d %d", &from, &to);
        tree[n+i+1].left = pos[from];
        tree[n+i+1].right = pos[to];
        tree[pos[from]].parent = n+i+1;
        tree[pos[to]].parent = n+i+1;
        pos[to] = n+i+1;
    }
    REP (i, k) {
        scanf("%d %d", &r[i].ST, &r[i].ND);
        if (r[i].ST > r[i].ND) swap(r[i].ST, r[i].ND);
    }

    fillTree();
    DFS(2*n-1, 0);
    initLCA();
    findTimes();
    simulate();

    printf("%lld\n", result);

    return 0;
}