#include <bits/stdc++.h>
using namespace std;
const int N = 2000010;
int st[N], w[N];
inline int gi() {
  int x = 0, o = 1;
  char ch = getchar();
  while (ch != '-' && (ch < '0' || ch > '9')) ch = getchar();
  if (ch == '-') ch = getchar(), o = -1;
  while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar();
  return x * o;
}
struct Dat {
  int p, c;
  inline bool operator<(const Dat &A) const { return p < A.p; }
} g[N];
struct Stack {
  int t;
  long long c, v[N << 1];
  inline void push(long long x) { v[++t] = x - c; }
  inline void pop() { --t; }
  inline long long top() { return v[t] + c; }
} p, q;
int main() {
  int n, m, cnt = 0;
  long long ans = 0, sum = 0;
  cin >> n >> m;
  for (int i = 1; i <= n; i++) g[++cnt] = (Dat){gi(), 0};
  for (int i = 1; i <= m; i++) {
    int x = gi(), y = gi();
    g[++cnt] = (Dat){x, y}, sum += y;
  }
  if (sum < n) {
    puts("-1");
    return 0;
  }
  sort(g + 1, g + 1 + cnt);
  for (int i = 1, tp = 0; i <= cnt; i++) {
    if (!g[i].c) {
      ++w[st[tp]];
      if (w[st[tp]] == g[st[tp]].c) --tp;
    } else
      st[++tp] = i;
  }
  for (int i = cnt, tp = 0; i; i--) {
    if (!g[i].c) {
      ++w[st[tp]];
      if (w[st[tp]] == g[st[tp]].c) --tp;
    } else if (w[i] != g[i].c)
      st[++tp] = i;
  }
  for (int i = 1; i <= cnt; i++) {
    int x = g[i].p;
    if (!g[i].c) {
      q.c -= x, q.push(ans - x);
      ans = 1LL << 60;
      if (p.t) {
        ans = min(ans, p.top() + x);
        p.pop(), p.c += x;
      }
    } else if (g[i].c && w[i]) {
      if (ans != 1LL << 60) p.c -= x, p.push(ans - x);
      if (q.t) {
        ans = min(ans, q.top() + x);
        q.pop(), q.c += x;
      }
      if (g[i].c > 1 || w[i] > 1) --g[i].c, --w[i], --i;
    }
  }
  cout << ans;
  return 0;
}
