#define _CRT_SECURE_NO_WARNINGS
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<string>
#include<stack>
#include<vector>
#define MAX 20
typedef long long ll;
using namespace std;
const int inf = 0x3f3f3f3f;
ll a[100010], b[100010];
ll k[1010], p[1010];
ll dp[1010][15];
int main()
{
    int n, m;
    while (scanf("%d%d", &n, &m) != EOF)
    {
        ll up1 = 0, up2 = 0, hp = 0;
        for (int i = 0; i < n; i++)
        {
            scanf("%lld%lld", &a[i], &b[i]);
            up1 = max(up1, b[i]);
            hp = max(hp, a[i]);
        }
        for (int i = 0; i < m; i++)
        {
            scanf("%lld%lld", &k[i], &p[i]);
            up2 = max(up2, p[i]);
        }
        if (up1 >= up2)
        {
            printf("-1\n");
            continue;
        }
        memset(dp, 0, sizeof(dp));
        for (int i = 0; i <= 10; i++)
        {
            for (int j = 1; j <= hp; j++)
            {
                dp[j][i] = inf;
                for (int u = 0; u < m; u++)
                {
                    int dmg = p[u] - i;
                    if (dmg <= 0)
                        continue;
                    if (dmg >= j)
                        dp[j][i] = min(dp[j][i], k[u]);
                    else
                        dp[j][i] = min(dp[j - dmg][i] + k[u], dp[j][i]);
                }
            }
        }
        ll ans = 0;
        for (int i = 0; i < n; i++)
            ans += dp[a[i]][b[i]];
        printf("%lld\n", ans);
    }
    return 0;
}