#include <bits/stdc++.h>
using namespace std;
const int maxn = 10500;
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;
}
char s[maxn];
char str[maxn];
int n, m, x, val, len;
bool judge(int p) {
  for (int i = 0; i < len; ++i)
    if (s[i + p] != str[i]) return false;
  return true;
}
void deal() {
  len = strlen(str);
  for (int i = 0; i <= n - len; ++i)
    if (judge(i)) addedge(i + 1, i + len + 1, 1, -val);
}
int main() {
  scanf("%d", &n);
  scanf("%s", s);
  scanf("%d", &m);
  init(n + 2);
  for (int i = 1; i <= m; ++i) {
    scanf("%s%d", str, &val);
    deal();
  }
  scanf("%d", &x);
  for (int i = 1; i <= n + 1; ++i) addedge(i - 1, i, x, 0);
  int cost;
  mincostmaxflow(0, n + 1, cost);
  printf("%d\n", -cost);
  return 0;
}
