#include <bits/stdc++.h>
using namespace std;
namespace io {
const int N = 1 << 20;
char buf[N], *t1 = buf, *t2 = buf;
inline int read() {
  static int an, f;
  an = 0, f = 1;
  static char ch;
  ch = t1 == t2 && (t2 = (t1 = buf) + fread(buf, 1, N, stdin), t1 == t2)
           ? EOF
           : *t1++;
  while (ch < 48 || ch > 57)
    ch == '-' ? f = -1 : 0,
                ch = t1 == t2 && (t2 = (t1 = buf) + fread(buf, 1, N, stdin),
                                  t1 == t2)
                         ? EOF
                         : *t1++;
  while (ch >= 48 && ch <= 57)
    an = (an << 3) + (an << 1) + (ch ^ 48),
    ch = t1 == t2 && (t2 = (t1 = buf) + fread(buf, 1, N, stdin), t1 == t2)
             ? EOF
             : *t1++;
  return an * f;
}
char buff[N], *T = buff;
void flush() {
  fwrite(buff, 1, T - buff, stdout);
  T = buff;
}
inline void putc(char ch) {
  if (T == buff + N) flush();
  *T++ = ch;
}
template <typename o>
inline void print(o x) {
  if (x < 0) putc('-'), x = -x;
  if (!x) return putc('0'), void();
  static int st[20], tp;
  while (x) st[++tp] = x % 10, x /= 10;
  while (tp) putc(st[tp] ^ 48), --tp;
}
}  // namespace io
using io::flush;
using io::print;
using io::putc;
using io::read;
struct stone {
  int p, w;
  friend bool operator<(stone a, stone b) { return a.p < b.p; }
} a[30];
int n, m, l, k, lim, c[10];
inline void upmin(long long &x, long long y) { x > y ? x = y : 0; }
const long long inf = 0x3f3f3f3f3f3f3f3fll;
struct matrix {
  long long a[128][128];
  friend matrix operator*(matrix a, matrix b) {
    static matrix c;
    for (int i = 0; i < lim; ++i)
      for (int j = 0; j < lim; ++j) {
        c.a[i][j] = inf;
        for (int k = 0; k < lim; ++k) upmin(c.a[i][j], a.a[i][k] + b.a[k][j]);
      }
    return c;
  }
} t[30];
struct data {
  long long a[128];
  friend data operator*(data a, matrix b) {
    static data c;
    for (int i = 0; i < lim; ++i) {
      c.a[i] = inf;
      for (int j = 0; j < lim; ++j) upmin(c.a[i], a.a[j] + b.a[j][i]);
    }
    return c;
  }
} s;
void trans(int d) {
  for (int i = 0; i <= 26; ++i)
    if (d >> i & 1) s = s * t[i];
}
int main() {
  n = read(), m = read(), l = read(), k = read();
  for (int i = 1; i <= m; ++i) c[i] = read();
  for (int i = 1; i <= k; ++i) a[i].p = read(), a[i].w = read();
  sort(a + 1, a + 1 + k);
  lim = 1 << (m - 1);
  for (int i = 0; i < lim; ++i)
    for (int j = 0; j < lim; ++j) t[0].a[i][j] = inf;
  for (int i = 0; i < lim; ++i) {
    if (__builtin_popcount(i) == n)
      t[0].a[i][i >> 1] = 0;
    else if (__builtin_popcount(i) == n - 1) {
      for (int j = 1; j <= m; ++j) {
        int x = i ^ (1 << (j - 1));
        if (__builtin_popcount(x) == n) t[0].a[i][x >> 1] = c[j];
      }
    }
  }
  for (int i = 1; i <= 26; ++i) t[i] = t[i - 1] * t[i - 1];
  for (int i = 0; i < lim; ++i) s.a[i] = inf;
  s.a[(1 << (n - 1)) - 1] = 0;
  int last = 1;
  for (int i = 1; i <= k && a[i].p <= l - n; ++i) {
    trans(a[i].p - last);
    last = a[i].p;
    for (int j = 0; j < lim; ++j)
      if (__builtin_popcount(j) == n - 1) s.a[j] += a[i].w;
  }
  trans(l - n + 1 - last);
  long long ans = s.a[(1 << (n - 1)) - 1];
  for (int i = 1; i <= k; ++i)
    if (a[i].p > l - n) ans += a[i].w;
  printf("%lld", ans);
  flush();
  return 0;
}
