import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.string;

void main() {
    auto s = readln.split.map!(to!int);
    auto N = s[0];
    auto M = s[1];
    auto U = readln.chomp;
    auto A = readln.split.map!(to!long).array;

    auto STB = M.iota.map!(_ => readln.split.map!(to!int).array).array;
    auto mp = new long[][](N, N);

    foreach (stb; STB) {
        int S = stb[0] - 1;
        int T = stb[1] - 1;
        long B = stb[2];
        if (S > T) swap(S, T);
        mp[S][T] += B;
    }

    auto source = N;
    auto sink = N + 1;
    auto FF = new FordFulkerson(N+2, source, sink);

    foreach (i; 0..N) {
        FF.add_edge(source, i, U[i] == 'L' ? A[i] : 0);
        FF.add_edge(i, sink, U[i] == 'L' ? 0 : A[i]);
    }


    foreach (i; 0..N) {
        foreach (j; i+1..N) {
            if (mp[i][j] == 0) continue;
            FF.add_edge(j, i, mp[i][j]);
        }
    }

    FF.run.writeln;
}


class FordFulkerson {
    int N, source, sink;
    int[][] adj;
    long[][] flow;
    bool[] used;

    this(int n, int s, int t) {
        N = n;
        source = s;
        sink = t;
        assert (s >= 0 && s < N && t >= 0 && t < N);
        adj = new int[][](N);
        flow = new long[][](N, N);
        used = new bool[](N);
    }

    void add_edge(int from, int to, long cap) {
        adj[from] ~= to;
        adj[to] ~= from;
        flow[from][to] = cap;
    }

    long dfs(int v, long min_cap) {
        if (v == sink)
            return min_cap;
        if (used[v])
            return 0;
        used[v] = true;
        foreach (to; adj[v]) {
            if (!used[to] && flow[v][to] > 0) {
                auto bottleneck = dfs(to, min(min_cap, flow[v][to]));
                if (bottleneck == 0) continue;
                flow[v][to] -= bottleneck;
                flow[to][v] += bottleneck;
                return bottleneck;
            }
        }
        return 0;
    }

    long run() {
        long ret = 0;
        while (true) {
            foreach (i; 0..N) used[i] = false;
            long f = dfs(source, long.max);
            if (f > 0)
                ret += f;
            else
                return ret;
        }
    }
}

