#include <bits/stdc++.h>
const int N = 100005;
using  namespace std;
typedef long long ll;
ll dp[1005][11];
ll a[N], b[N], k[N], p[N];
int main() {
    ll n, m;
    while (cin >> n >> m) {
        ll maxn = 0, maxm = 0;
        for (ll i = 0; i < n; ++i) {
            cin >> a[i] >> b[i];
            maxn = max(maxn, b[i]);
        }
        for (ll i = 0; i < m; ++i) {
            cin >> k[i] >> p[i];
            maxm = max(maxm, p[i]);
        }
        if (maxn >= maxm) {
            cout << -1 << '\n';
            continue;
        }
        memset(dp, 0x3f, sizeof dp);
        for (ll j = 0; j <= 10; ++j) {
            for (ll i = 1; i < 1005; ++i) {
                for (ll l = 0; l < m; ++l) {
                    ll tmp = p[l] - j;
                    if (tmp <= 0) {
                        continue;
                    }
                    if (tmp >= i) {
                        dp[i][j] = min(dp[i][j], k[l]);
                    } else {
                        dp[i][j] = min(dp[i][j], dp[i - tmp][j] + k[l]);
                    }
                }
            }
        }
        ll res = 0;
        for (ll i = 0; i < n; ++i) {
            res += dp[a[i]][b[i]];
        }
        cout << res << '\n';
    }
    return 0;
}