#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pii pair<int, int>
ll dp[15][1085];
int num[15][1085];
pii s[1005];
int main()
{
    int n, m, u, v;
//    memset(dp, 63, sizeof(dp));
//    cout << dp[1][1] << endl << 0x3f3f3f3f3f3f3f3f << endl;
    while(scanf("%d%d", &n, &m) != EOF)
    {
        memset(num, 0, sizeof(num));
        int mv = 0, mg = 0;
        for(int i = 1; i <= n; i++)
        {
            scanf("%d%d", &u, &v);
            mv = max(v, mv);
            num[v][u]++;
        }
        for(int i = 1; i <= m; i++)
        {
            scanf("%d%d", &s[i].first, &s[i].second);
            mg = max(mg, s[i].second);
        }
        if(mg <= mv)
        {
            puts("-1");
            continue;
        }
        int flag = 0;
        ll ans = 0;
        memset(dp, 63, sizeof(dp));
        for(int i = 0; i <= mv; i++) dp[i][0] = 0;

        for(int i = 0; i <= mv; i++)
            for(int j = 1; j <= 1000; j++)
            {
//                if(num[i][j] == 0) continue;
//                cout << i << " " << j << "  ....\n";
                for(int k = 1; k <= m; k++)
                {
              //      if(s[k].second - i <= 0) continue;

                    if(s[k].second - i >= j)
                    {
                        dp[i][j] = min(dp[i][j], s[k].first * 1LL);
                        continue;
                    }

                    if(dp[i][j-(s[k].second - i)] == 0x3f3f3f3f3f3f3f3f) continue;

                    dp[i][j] = min(dp[i][j], dp[i][j-(s[k].second - i)] + s[k].first);
                }
                if(dp[i][j] == 0x3f3f3f3f3f3f3f3f && num[i][j] != 0)
                {
                    flag = 1;
                }
                ans = ans + 1LL * dp[i][j] * num[i][j];
            }
        if(flag)
            printf("-1\n");
        else
            cout << ans << endl;

    }
    return 0;
}