#include <bits/stdc++.h>
using namespace std;
const int maxn = (1e6 + 7) * 4;
const int mod = 1e9 + 7;
const int inf = 2e9;
using namespace std;
string s, ms[1000];
int v[1000];
const int MAXN = 10000;
const int MAXM = 100000;
const int INF = 0x3f3f3f3f;
struct Edge {
  int to, next, cap, flow, cost;
} edge[MAXM];
int head[MAXN], tol;
int pre[MAXN], dis[MAXN];
bool vis[MAXN];
int N;
void init(int n) {
  N = n;
  tol = 0;
  memset(head, -1, sizeof(head));
}
void addedge(int u, int v, int cap, int cost) {
  edge[tol].to = v;
  edge[tol].cap = cap;
  edge[tol].cost = cost;
  edge[tol].flow = 0;
  edge[tol].next = head[u];
  head[u] = tol++;
  edge[tol].to = u;
  edge[tol].cap = 0;
  edge[tol].cost = -cost;
  edge[tol].flow = 0;
  edge[tol].next = head[v];
  head[v] = tol++;
}
bool spfa(int s, int t) {
  queue<int> q;
  for (int i = 0; i < N; i++) {
    dis[i] = INF;
    vis[i] = false;
    pre[i] = -1;
  }
  dis[s] = 0;
  vis[s] = true;
  q.push(s);
  while (!q.empty()) {
    int u = q.front();
    q.pop();
    vis[u] = false;
    for (int i = head[u]; i != -1; i = edge[i].next) {
      int v = edge[i].to;
      if (edge[i].cap > edge[i].flow && dis[v] > dis[u] + edge[i].cost) {
        dis[v] = dis[u] + edge[i].cost;
        pre[v] = i;
        if (!vis[v]) {
          vis[v] = true;
          q.push(v);
        }
      }
    }
  }
  if (pre[t] == -1)
    return false;
  else
    return true;
}
int minCostMaxflow(int s, int t, int &cost) {
  int flow = 0;
  cost = 0;
  while (spfa(s, t)) {
    int Min = INF;
    for (int i = pre[t]; i != -1; i = pre[edge[i ^ 1].to]) {
      if (Min > edge[i].cap - edge[i].flow) Min = edge[i].cap - edge[i].flow;
    }
    for (int i = pre[t]; i != -1; i = pre[edge[i ^ 1].to]) {
      edge[i].flow += Min;
      edge[i ^ 1].flow -= Min;
      cost += edge[i].cost * Min;
    }
    flow += Min;
  }
  return flow;
}
void build(int x) {
  string t = ms[x];
  int siz = t.size();
  for (int i = 0; i < s.size(); i++) {
    if (siz + i <= s.size() && t == s.substr(i, siz)) {
      addedge(i, i + siz, 1, -v[x]);
    }
  }
}
int main() {
  ios::sync_with_stdio(false);
  ;
  int n, m, x;
  cin >> n >> s >> m;
  int f_start = n + 1;
  int f_end = n;
  init(n + 2);
  for (int i = 0; i < m; i++) cin >> ms[i] >> v[i], build(i);
  cin >> x;
  addedge(f_start, 0, x, 0);
  addedge(n - 1, f_end, x, 0);
  for (int i = 0; i < n - 1; i++) addedge(i, i + 1, x, 0);
  int ans = 0;
  minCostMaxflow(f_start, f_end, ans);
  cout << -ans << endl;
  return 0;
}
