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#include <iostream>
#include <cctype>
#include <set>
#include <vector>
#include <algorithm>

#ifndef _MSC_VER
#define __int64 long long
#endif

typedef unsigned int uint;
typedef unsigned __int64 uint64;

uint get_uint()
{
	int c;
	while (isspace(c = std::cin.get()));

	uint value = (c - '0');

	while (isdigit(c = std::cin.get()))
	{
		value = (10 * value) + (c - '0');
	}

	return value;
}

typedef std::set<uint> uint_set;
typedef std::vector<uint> uint_vector;

uint g[200002];
uint a[200002], b[200002];
uint c[500002], d[500002];

uint_set react[200002];
uint_vector need[200002];

bool done[500002];

int main()
{
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(0);

	uint n = get_uint();
	uint m = get_uint();
	uint k = get_uint();

	for (uint i = 0; i < n; ++i)
	{
		g[i + 1] = get_uint();
	}

	for (uint i = 0; i < m; ++i)
	{
		a[i] = get_uint();
		b[i] = get_uint();
	}

	for (uint i = 0; i < k; ++i)
	{
		c[i] = get_uint();
		d[i] = get_uint();

		react[c[i]].insert(i);
		react[d[i]].insert(i);

		need[c[i]].push_back(i);
		need[d[i]].push_back(i);
	}

	uint64 result = 0;

	for (uint i = 0; i < m; ++i)
	{
		uint from = a[i];
		uint to = b[i];

		uint_set &react_from = react[from];
		uint_set &react_to = react[to];

		if (react_from.size() > react_to.size())
		{
			std::swap(react_from, react_to);
		}

		for (auto x : react_from)
		{
			if (react_to.count(x))
			{
				uint update = std::min(g[c[x]], g[d[x]]);

				result += update;

				g[c[x]] -= update;
				g[d[x]] -= update;

				if (g[c[x]] == 0)
				{
					for (auto y : need[c[x]])
					{
						done[y] = true;
					}
				}

				if (g[d[x]] == 0)
				{
					for (auto y : need[d[x]])
					{
						done[y] = true;
					}
				}
			}
			else if (!done[x])
			{
				react_to.insert(x);
			}
		}

		react_from.clear();
	}

	std::cout << result * 2 << std::endl;

	return 0;
}