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/*
 * Uzylem algorytmu:
 * http://en.wikipedia.org/wiki/Tarjan%27s_off-line_lowest_common_ancestors_algorithm
 * 
 */
#include <cstdio>
#include <algorithm>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <cmath>
#include <map>
#include <string>
#include <set>
#include <cstring>
#include <iostream>
#include <sstream>
#include <cassert>
using namespace std;

#define PB push_back
#define FORE(i,t) for(typeof(t.begin())i=t.begin();i!=t.end();++i)
#define SZ(x) int((x).size())
#define REP(i,n) for(int i=0,_=(n);i<_;++i)
#define FOR(i,a,b) for(int i=(a),_=(b);i<=_;++i)
#define FORD(i,a,b) for(int i=(a),_=(b);i>=_;--i)

typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;

const int INF = 1e9 + 9;

const int N = 200002;
const int K = 500002;

struct Reaction {
  int a, b;
  pii priority;

  bool operator<(const Reaction &other) const {
    return priority < other.priority;
  }
};

vi grams(N);
vector<vi> children(N);
vi parent(N, -1);
vector<vector<pii> > queries(N);
vi ancestor(N);
vi fu_parent(N);
vector<int> color(N);
vector<vector<Reaction> > reactions(N);
vector<pii> visited(N);

vector<pii> sequence;

void visit(int x, int &t) {
  visited[x].first = t++;

  FORE(yt, children[x]) {
    int y = *yt;
    visit(y, t);
  }
  visited[x].second = t++;
}

void fu_makeset(int x) {
  fu_parent[x] = -1;
}

int fu_find(int x) {
  if (fu_parent[x] < 0)
    return x;
  return fu_parent[x] = fu_find(fu_parent[x]);
}

void fu_union(int x, int y) {
  x = fu_find(x), y = fu_find(y);
  if (fu_parent[x] < fu_parent[y])
    fu_parent[y] = x;
  else if (fu_parent[x] > fu_parent[y])
    fu_parent[x] = y;
  else if (x != y) {
    fu_parent[y] = x;
    --fu_parent[x];
  }
}

void tarjan(int u, int clr) {
  fu_makeset(u);
  ancestor[u] = u;
  FORE(vt, children[u]) {
    int v = *vt;
    tarjan(v, clr);
    fu_union(u, v);
    ancestor[fu_find(u)] = u;
  }
  color[u] = clr;

  FORE(vt, queries[u]) {
    int v = vt->first;
    int reaction_id = vt->second;
    if (color[v] == clr) {
      int anc = ancestor[fu_find(v)];
      reactions[anc].PB((Reaction) {
        u, v, pii(INF, reaction_id)
      });
    }
  }
}

int entry_time(int u, int w) {
  int a = 0;
  int b = SZ(children[u]) - 1;
  int w_time = visited[w].first;
  if (u == w) {
    return w_time;
  }
  while (a <= b) {
    int d = (a + b) / 2;
    int d_time = visited[children[u][d]].first;
    if (d_time <= w_time) {
      a = d + 1;
    } else {
      b = d - 1;
    }
  }
  return visited[children[u][b]].first;
}

void inline jeden() {
  int n, m, k;
  scanf("%d%d%d", &n, &m, &k);

  FOR(i, 1, n) {
    scanf("%d", &grams[i]);
  }

  REP(i, m) {
    int a, b;
    scanf("%d%d", &a, &b);
    children[b].PB(a);
    parent[a] = b;
    sequence.PB(pii(a, b));
  }

  REP(i, k) {
    int a, b;
    scanf("%d%d", &a, &b);
    queries[a].PB(pii(b, i));
    queries[b].PB(pii(a, i));
  }

  {
    int visit_time = 0;

    FOR(i, 1, n) {
      if (parent[i] == -1) {
        tarjan(i, i);
        visit(i, visit_time);
      }
    }
  }

  vi final_list;

  REP(i, m) {
    int u = sequence[i].first;
    final_list.PB(u);
  }

  FOR(i, 1, n) {
    if (parent[i] == -1) {
      final_list.PB(i);
    }
  }

  ll result = 0;

  FORE(ut, final_list) {
    int u = *ut;
    FORE(r, reactions[u]) {
      r->priority.first = max(
              entry_time(u, r->a),
              entry_time(u, r->b));
    }
    sort(reactions[u].begin(), reactions[u].end());

    FORE(r, reactions[u]) {
      int amount = min(grams[r->a], grams[r->b]);
      result += 2LL * amount;
      grams[r->a] -= amount;
      grams[r->b] -= amount;
    }
  }
  printf("%lld\n", result);
}

int main() {
  //int z; scanf("%d", &z); while(z--)
  jeden();
}