//#define NDEBUG
#include <cstddef>
#include <cstdint>
#include <vector>

using i8 = ::std::int_least8_t;
using i32 = ::std::int_least32_t;
using i64 = ::std::int_least64_t;
using u8 = ::std::uint_least8_t;
using u32 = ::std::uint_least32_t;
using u64 = ::std::uint_least64_t;
using isize = ::std::ptrdiff_t;
using usize = ::std::size_t;

template <class T = usize> class rep {
	const T f, l;

public:
	class itr {
		friend rep;
		T i;
		constexpr itr(T x) noexcept : i(x) {}

	public:
		void operator++() noexcept { ++i; }
		constexpr T operator*() const noexcept { return i; }
		constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
	};
	constexpr rep(const T first, const T last) noexcept : f(first), l(last) {}
	constexpr itr begin() const noexcept { return itr(f); }
	constexpr itr end() const noexcept { return itr(l); }
};
template <class T = usize> class revrep {
	const T f, l;

public:
	class itr {
		friend revrep;
		T i;
		constexpr itr(T x) noexcept : i(x) {}

	public:
		void operator++() noexcept { --i; }
		constexpr T operator*() const noexcept { return i; }
		constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
	};
	constexpr revrep(const T first, const T last) noexcept : f(first), l(last) {}
	constexpr itr begin() const noexcept { return itr(l - 1); }
	constexpr itr end() const noexcept { return itr(f - 1); }
};
template <class T> bool amax(T &a, const T &b) {
	return a <= b ? (a = b, 1) : 0;
}
template <class T> bool amin(T &a, const T &b) {
	return b <= a ? (a = b, 1) : 0;
}
template <class T> bool asmax(T &a, const T &b) {
	return b <= a ? 0 : (a = b, 1);
}
template <class T> bool asmin(T &a, const T &b) {
	return a <= b ? 0 : (a = b, 1);
}
template <class T> using vec_alias = ::std::vector<T>;
template <class T> auto md_vec(usize n, const T &value) {
	return ::std::vector<T>(n, value);
}
template <class... Args> auto md_vec(usize n, Args... args) {
	return ::std::vector<decltype(md_vec(args...))>(n, md_vec(args...));
}
template <class T> const T &as_const(const T &v) noexcept { return v; }
template <class T> constexpr T difference(const T &a, const T &b) {
	return a <= b ? b - a : a - b;
}

#include <cassert>
#include <iterator>
#include <utility>

template <class Monoid, template <class> class Container> class segment_tree {
public:
	using value_structure = Monoid;
	using value_type = typename value_structure::value_type;
	using container_type = Container<value_type>;
	using const_reference = typename container_type::const_reference;
	using size_type = typename container_type::size_type;

protected:
	static size_type getsize(const size_type size) {
		size_type ret = 1;
		while (ret < size)
			ret <<= 1;
		return ret;
	}

	size_type size_;
	container_type tree;

	size_type base_size() const { return tree.size() >> 1; }
	void recalc(const size_type index) {
		tree[index] =
			value_structure::operation(tree[index << 1], tree[index << 1 | 1]);
	}

public:
	segment_tree() : size_(0), tree() {}
	explicit segment_tree(const size_type size)
		: size_(size), tree(getsize(size) << 1, value_structure::identity()) {}
	template <class InputIterator>
	segment_tree(InputIterator first, InputIterator last)
		: size_(::std::distance(first, last)), tree() {
		const size_type cap = getsize(size_);
		tree.reserve(cap << 1);
		tree.resize(cap, value_structure::identity());
		tree.insert(tree.end(), first, last);
		tree.resize(cap << 1, value_structure::identity());
		for (size_type i = cap - 1; i; --i)
			recalc(i);
	}

	bool empty() const { return !size_; }
	size_type size() const { return size_; }

	const_reference operator[](const size_type index) const {
		assert(index < size());
		return tree[index + base_size()];
	}
	value_type fold(size_type first, size_type last) const {
		assert(first <= last);
		assert(first <= size());
		assert(last <= size());
		value_type ret_l = value_structure::identity(),
			ret_r = value_structure::identity();
		for (first += base_size(), last += base_size(); first < last;
			first >>= 1, last >>= 1) {
			if (first & 1)
				ret_l = value_structure::operation(::std::move(ret_l), tree[first++]);
			if (last & 1)
				ret_r = value_structure::operation(tree[last - 1], ::std::move(ret_r));
		}
		return value_structure::operation(::std::move(ret_l), ::std::move(ret_r));
	}
	template <class F> size_type search(const F &f) const {
		if (f(value_structure::identity()))
			return 0;
		if (!f(tree[1]))
			return size() + 1;
		value_type acc = value_structure::identity();
		size_type i = 1;
		while (i < base_size())
			if (!f(value_structure::operation(acc, tree[i <<= 1])))
				acc = value_structure::operation(::std::move(acc), tree[i++]);
		return i - base_size() + 1;
	}

	template <class F> void update(size_type index, const F &f) {
		assert(index < size());
		index += base_size();
		tree[index] = f(::std::move(tree[index]));
		while (index >>= 1)
			recalc(index);
	}
};



#include <algorithm>
#include <iostream>
#include <utility>
#include <numeric>
#include <set>
#include<array>
#include<queue>

namespace std {
	u64 inf = static_cast<u64>(1) << 55;

	struct max_flow {
		struct edge { int to;u64 cap;int rev; };
		int V;
		vector<vector<edge>> G;
		vector<int> itr, level;

		max_flow(u64 V) : V(V) { G.assign(V, vector<edge>()); }

		void add_edge(int from, int to, u64 cap) {
			G[from].push_back({ to, cap, (int)G[to].size() });
			G[to].push_back({ from, 0, (int)G[from].size() - 1 });
		}

		void bfs(int s) {
			level.assign(V, -1);
			queue<int> q;
			level[s] = 0; q.push(s);
			while (!q.empty()) {
				int v = q.front(); q.pop();
				for (auto &e : G[v]) {
					if (e.cap > 0 && level[e.to] < 0) {
						level[e.to] = level[v] + 1;
						q.push(e.to);
					}
				}
			}
		}

		u64 dfs(int v, int t, u64 f) {
			if (v == t) return f;
			for (int& i = itr[v]; i < (int)G[v].size(); ++i) {
				edge& e = G[v][i];
				if (e.cap > 0 && level[v] < level[e.to]) {
					u64 d = dfs(e.to, t, min(f, e.cap));
					if (d > 0) {
						e.cap -= d;
						G[e.to][e.rev].cap += d;
						return d;
					}
				}
			}
			return 0;
		}

		u64 run(int s, int t) {
			u64 ret = 0, f;
			while (bfs(s), level[t] >= 0) {
				itr.assign(V, 0);
				while ((f = dfs(s, t, inf)) > 0) ret += f;
			}
			return ret;
		}
	};
}

#include<string>

int main() {
	usize n, m;
	std::cin >> n >> m;

	std::max_flow f(n + 2);
	const usize l = n, r = n + 1;

	std::string u;
	std::cin >> u;
	for (const auto i : rep<>(0, n)) {
		u64 a;
		std::cin >> a;
		if (u[i] == 'L') {
			f.add_edge(l, i, a);
		}
		else {
			f.add_edge(i, r, a);
		}
	}

	while (m--) {
		usize s, t;
		u64 b;
		std::cin >> s >> t >> b;
		--s;
		--t;
		if (s > t) {
			std::swap(s, t);
		}
		f.add_edge(t, s, b);
	}

	std::cout << f.run(l, r) << std::endl;

	return 0;
}



Measured memory_bytes: 3280