#include <bits/stdc++.h>
using namespace std;
struct ZKW_flow {
  int S, T, ecnt;
  int head[200100];
  int c[2000200], w[2000200], to[2000200], next[2000200];
  ZKW_flow() {
    memset(head, 0, sizeof(head));
    ecnt = 2;
  }
  void add_edge(int u, int v, int _c, int ww) {
    c[ecnt] = _c;
    w[ecnt] = ww;
    to[ecnt] = v;
    next[ecnt] = head[u];
    head[u] = ecnt++;
    c[ecnt] = 0;
    w[ecnt] = -ww;
    to[ecnt] = u;
    next[ecnt] = head[v];
    head[v] = ecnt++;
  }
  int dis[200100];
  void SPFA() {
    for (int i = 1; i <= T; ++i) dis[i] = 0x3f3f3f3f;
    priority_queue<pair<int, int> > Q;
    dis[S] = 0;
    Q.push(make_pair(0, S));
    while (!Q.empty()) {
      int u = Q.top().second, d = -Q.top().first;
      Q.pop();
      if (dis[u] != d) continue;
      for (int p = head[u]; p; p = next[p]) {
        int &v = to[p];
        if (c[p] && dis[v] > d + w[p]) {
          dis[v] = d + w[p];
          Q.push(make_pair(-dis[v], v));
        }
      }
    }
    for (int i = 1; i <= T; ++i) dis[i] = dis[T] - dis[i];
  }
  int ans;
  bool use[200100];
  int add_flow(int u, int flow) {
    if (u == T) {
      ans += dis[S] * flow;
      return flow;
    }
    use[u] = true;
    int now = flow;
    for (int p = head[u]; p; p = next[p]) {
      int &v = to[p];
      if (c[p] && !use[v] && dis[u] == dis[v] + w[p]) {
        int tmp = add_flow(v, min(now, c[p]));
        c[p] -= tmp;
        c[p ^ 1] += tmp;
        now -= tmp;
        if (!now) break;
      }
    }
    return flow - now;
  }
  bool modify_label() {
    int d = 0x3f3f3f3f;
    for (int u = 1; u <= T; ++u)
      if (use[u])
        for (int p = head[u]; p; p = next[p]) {
          int &v = to[p];
          if (c[p] && !use[v]) d = min(d, dis[v] + w[p] - dis[u]);
        }
    if (d == 0x3f3f3f3f) return false;
    for (int i = 1; i <= T; ++i)
      if (use[i]) dis[i] += d;
    return true;
  }
  int solve() {
    SPFA();
    while (true) {
      while (true) {
        for (int i = 1; i <= T; ++i) use[i] = 0;
        if (!add_flow(S, 0x3f3f3f3f)) break;
      }
      if (!modify_label()) break;
    }
    return ans;
  }
} MCMF;
const int N = 550;
char str[N], pat[N][N];
int p[N];
struct Data {
  int id, l, r, val;
  Data(int id = 0, int l = 0, int r = 0, int val = 0)
      : id(id), l(l), r(r), val(val) {}
  bool operator<(const Data &d) const {
    if (l != d.l) return l < d.l;
    if (r != d.r) return r < d.r;
    if (id != d.id) return id < d.id;
    return val < d.val;
  }
} P[N * N];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  int n;
  cin >> n >> str + 1;
  int m;
  cin >> m;
  for (int i = 1; i <= m; i++) cin >> pat[i] >> p[i];
  int k;
  cin >> k;
  int inc = 0;
  for (int i = 1; i <= n; i++) {
    for (int j = 1; j <= m; j++)
      if (!strncmp(str + i, pat[j], strlen(pat[j]))) {
        inc++;
        P[inc] = Data(inc, i, i + strlen(pat[j]) - 1, p[j]);
      }
  }
  sort(P + 1, P + inc + 1);
  int src = inc + inc + 1;
  MCMF.S = src + 1, MCMF.T = MCMF.S + 1;
  for (int i = 1; i <= inc; i++) {
    int u = P[i].id, v = 0;
    auto it =
        lower_bound(P + 1, P + inc + 1, Data(0, P[i].r + 1, P[i].r + 1, 0));
    while (it < P + inc + 1) {
      v = it->id;
      MCMF.add_edge(u + inc, v, 1, 0);
      it++;
    }
  }
  for (int i = 1; i <= inc; i++)
    MCMF.add_edge(P[i].id, P[i].id + inc, 1, -P[i].val);
  for (int i = 1; i <= inc; i++)
    MCMF.add_edge(src, P[i].id, 1, 0),
        MCMF.add_edge(P[i].id + inc, MCMF.T, 1, 0);
  MCMF.add_edge(MCMF.S, src, k, 0);
  cout << -MCMF.solve() << endl;
  return 0;
}
