#include <bits/stdc++.h>
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << std::endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
namespace MCMF {
const int MAXV = int(1e5) + 10, MAXE = int(2e5) + 10;
const long long int INF = 1e18;
int V, E;
int last[MAXV], how[MAXV];
long long int dist[MAXV], pi[MAXV];
int next[MAXE], from[MAXE], adj[MAXE];
long long int cap[MAXE], cost[MAXE];
void init(int n) {
  V = n;
  E = 0;
  for (int i = (0); i < (V); ++i) last[i] = -1, pi[i] = 0;
}
void AddEdge(int x, int y, long long int c, long long int w) {
  from[E] = x;
  adj[E] = y;
  cap[E] = c;
  cost[E] = +w;
  next[E] = last[x];
  last[x] = E++;
  from[E] = y;
  adj[E] = x;
  cap[E] = 0;
  cost[E] = -w;
  next[E] = last[y];
  last[y] = E++;
}
int cnt_q[MAXV], Q[MAXV], qlen;
bool in_q[MAXV];
bool SPFA(int s, int t) {
  for (int i = (0); i < (V); ++i) dist[i] = INF, cnt_q[i] = in_q[i] = 0;
  qlen = 0;
  Q[qlen++] = s;
  dist[s] = 0;
  cnt_q[s] = 1;
  in_q[s] = 1;
  while (qlen) {
    int u = Q[--qlen];
    in_q[u] = 0;
    for (int e = last[u]; e >= 0; e = next[e]) {
      if (cap[e] == 0) continue;
      int w = adj[e];
      long long int val = dist[u] + pi[u] + cost[e] - pi[w];
      if (val >= dist[w]) continue;
      dist[w] = val;
      how[w] = e;
      if (in_q[w]) continue;
      in_q[w] = 1;
      cnt_q[w]++;
      Q[qlen++] = w;
    }
  }
  return dist[t] < INF / 2;
}
pair<long long int, long long int> run(int src, int sink) {
  long long int total = 0;
  long long int flow = 0;
  while (SPFA(src, sink)) {
    long long int aug = cap[how[sink]];
    for (int i = sink; i != src; i = from[how[i]]) aug = min(aug, cap[how[i]]);
    for (int i = sink; i != src; i = from[how[i]]) {
      cap[how[i]] -= aug;
      cap[how[i] ^ 1] += aug;
      total += cost[how[i]] * aug;
    }
    flow += aug;
    for (int i = (0); i < (V); ++i) pi[i] = min(pi[i] + dist[i], INF);
  }
  return make_pair(flow, total);
}
}  // namespace MCMF
const int N = 505;
const int MAX = int(1e5) + 10;
int nfa[N];
void build_NFA(string& s) {
  nfa[0] = 0;
  int x = 0, n = (int)(s.size());
  for (int i = 1; i <= n; i++) {
    nfa[i] = x;
    while (i != n) {
      if (s[x] == s[i]) {
        x++;
        break;
      }
      if (!x) break;
      x = nfa[x];
    }
  }
}
int kmp_search(int start, string& P, string& T) {
  for (int i = start, x = 0; i < (int)(T.size());) {
    if (T[i] == P[x])
      x++, i++;
    else if (!x)
      i++;
    else
      x = nfa[x];
    if (x == (int)(P.size())) return i - (int)(P.size());
  }
  return -1;
}
string s;
int L[MAX], R[MAX], C[MAX], len, deg[N];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  cin >> s;
  int m;
  cin >> m;
  for (int i = 1; i <= m; i++) {
    string t;
    int c;
    cin >> t >> c;
    int ans = 0;
    build_NFA(t);
    while ((ans = kmp_search(ans, t, s)) != -1) {
      L[len] = 1 + ans, R[len] = 2 + ans + (int)(t.size()) - 1, C[len] = c;
      len++;
      ans += (int)(t.size()) - nfa[(int)(t.size())];
    }
  }
  int x;
  cin >> x;
  MCMF::init(n + 3);
  MCMF::AddEdge(0, 1, x, 0);
  MCMF::AddEdge(n + 1, n + 2, x, 0);
  for (int i = 0; i < len; i++) {
    MCMF::AddEdge(L[i], R[i], 1, -C[i]);
  }
  for (int i = 1; i <= n; i++) MCMF::AddEdge(i, i + 1, x, 0);
  long long int ans = MCMF::run(0, n + 2).second;
  cout << -ans << endl;
  return 0;
}
