#include <bits/stdc++.h>
using namespace std;
char buf[1 << 21], *p1 = buf, *p2 = buf;
template <class T>
void read(T &x) {
  x = 0;
  int c = getchar();
  int flag = 0;
  while (c < '0' || c > '9') flag |= (c == '-'), c = getchar();
  while (c >= '0' && c <= '9')
    x = (x << 3) + (x << 1) + (c ^ 48), c = getchar();
  if (flag) x = -x;
}
template <class T>
T _max(T a, T b) {
  return b < a ? a : b;
}
template <class T>
T _min(T a, T b) {
  return a < b ? a : b;
}
template <class T>
bool checkmax(T &a, T b) {
  return a < b ? a = b, 1 : 0;
}
template <class T>
bool checkmin(T &a, T b) {
  return b < a ? a = b, 1 : 0;
}
const long long inf = 0x3f3f3f3f3f3f3f3f;
int x, k, n, q;
int c[10];
int tot = 0, rnk[256], bin[80];
pair<int, int> f[30];
struct mat {
  int n;
  long long a[72][72];
  void init(int m, long long v = inf) {
    n = m;
    for (int i = 1; i <= n; ++i)
      for (int j = 1; j <= n; ++j) a[i][j] = inf;
  }
} A, B;
mat operator*(mat a, mat b) {
  int n = a.n;
  mat c;
  c.init(n);
  for (int i = 1; i <= n; ++i)
    for (int k = 1; k <= n; ++k)
      if (a.a[i][k] < inf)
        for (int j = 1; j <= n; ++j)
          if (b.a[k][j] < inf) checkmin(c.a[i][j], a.a[i][k] + b.a[k][j]);
  return c;
}
mat operator^(mat a, int b) {
  mat ans = a;
  --b;
  while (b) {
    if (b & 1) ans = ans * a;
    a = a * a;
    b >>= 1;
  }
  return ans;
}
void init() {
  read(x);
  read(k);
  read(n);
  read(q);
  for (int i = 1; i <= k; ++i) read(c[i]);
  for (int S = 0; S < (1 << k); ++S) {
    int cnt = 0;
    for (int i = 0; i < k; ++i)
      if (S >> i & 1) ++cnt;
    if (cnt == x) {
      rnk[S] = ++tot;
      bin[tot] = S;
    }
  }
  A.init(tot);
  B.init(tot);
  A.a[1][1] = 0;
  for (int i = 1; i <= tot; ++i) {
    int S = bin[i];
    if (S & 1) {
      for (int o = 1; o <= k; ++o)
        if (!(S >> o & 1)) {
          B.a[i][rnk[(S | (1 << o)) >> 1]] = c[o];
        }
    } else {
      B.a[i][rnk[S >> 1]] = 0;
    }
  }
  for (int i = 1; i <= q; ++i) read(f[i].first), read(f[i].second);
  sort(f + 1, f + q + 1);
}
void solve() {
  int pre = 1;
  long long value = 0;
  for (int i = 1; i <= q; ++i) {
    if (f[i].first > n - x) {
      value += f[i].second;
      continue;
    }
    int len = f[i].first - pre;
    pre = f[i].first;
    if (len) A = A * (B ^ len);
    for (int j = 1; j <= tot; ++j)
      if (bin[j] & 1) A.a[1][j] += f[i].second;
  }
  if (pre <= n - x) A = A * (B ^ (n - x - pre + 1));
  long long ans = A.a[1][1] + value;
  printf("%lld\n", ans);
}
int main() {
  init();
  solve();
  return 0;
}
