#include <bits/stdc++.h>
using namespace std;
const long long inf = 1e18;
pair<int, int> in[10015];
long long dp[2][10015];
int tmp[10015];
void solve() {
  int n, m;
  scanf("%d %d ", &n, &m);
  for (int i = 1; i <= n; ++i) {
    scanf("%d ", &in[i].first);
    in[i].second = -1;
  }
  int sum = 0;
  int maxCount = n;
  for (int i = n + 1; i <= n + m; ++i) {
    scanf("%d %d ", &in[i].first, &in[i].second);
    sum += in[i].second;
    maxCount = max(maxCount, in[i].second);
  }
  if (sum < n) {
    printf("-1\n");
    return;
  }
  sort(in + 1, in + n + m + 1);
  in[0].first = in[1].first;
  int p = 0;
  for (int i = n + 1; i <= n + maxCount; ++i) {
    dp[p][i] = inf;
  }
  for (int i = 1; i <= n + m; ++i) {
    p ^= 1;
    for (int j = 0; j <= n + maxCount; ++j) {
      long long s = min(n + maxCount, max(j - in[i].second, 0));
      dp[p][j] = dp[p ^ 1][s] + (in[i].first - in[i - 1].first) * abs(n - s);
    }
    for (int j = n + maxCount; j; --j) {
      dp[p][j - 1] = min(dp[p][j - 1], dp[p][j]);
    }
  }
  printf("%lld\n", dp[p][n]);
}
int main() {
  solve();
  return 0;
}
