#include <bits/stdc++.h>
using namespace std;
#define max 1e18
int k[1005],p[1005],a[100010],b[100010];
long long dp[15][1005]; 
int main()
{
    long long n, m;
    while (cin >> n >> m)
    {
        for (int i = 1; i <= n; i++)
            cin >> a[i] >> b[i];
        for (int i = 1; i <= m; i++)
            cin >> k[i] >> p[i];
        for (int i = 0; i <= 10; i++)
        {
            for (int j = 1; j <= 1000; j++)
                dp[i][j] = max;
            dp[i][0] = 0;
            for (int j = 1; j <= m; j++)
            {
                if (p[j] <= i)
                    continue;
                for (int q = 1; q <= 1000; q++)
                {
                    int x;
                    if (q - p[j] + i > 0)
                        x = q - p[j] + i;
                    else
                        x = 0;
                    dp[i][q] = min(dp[i][x] + k[j], dp[i][q]);
                }
            }
        }
        long long ans = 0;
        for (int i = 1; i <= n; i++)
            ans += dp[b[i]][a[i]];
        if (ans >= max)
            cout << -1 << endl;
        else
            cout << ans << endl;
    }
    return 0;
}