#include <iostream>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#define inf 1000000007
#define maxn 1005
#define maxm 100005
#define maxb 11
#define ll long long
using namespace std; 
int dp[maxb][maxn];
int n, m, a[maxm], b[maxm], k[maxn], p[maxn];
int main()
{
    while(scanf("%d%d", &n, &m) != EOF)
    {
        for(int i = 1; i <= n; i++) scanf("%d%d", &a[i], &b[i]);
        for(int i = 1; i <= m; i++) scanf("%d%d", &k[i], &p[i]);
        for(int i = 0; i < maxb; i++)
        {
            dp[i][0] = 0;
            for(int j = 1; j < maxn; j++) dp[i][j] = inf;
        }
        for(int i = 1; i <= m; i++)
            for(int j = 0; j < maxb && j < p[i]; j++)
                for(int l = 0; l < maxn; l++)
                {
                    int ed = l - (p[i] - j);
                    if(ed <= 0) dp[j][l] = min(dp[j][l], k[i]);
                    else dp[j][l] = min(dp[j][l], k[i] + dp[j][ed]);
                }
        ll ans = 0;
        bool flag = 1;
        for(int i = 1; i <= n; i++)
            if(dp[b[i]][a[i]] == inf) flag = 0;
            else ans += dp[b[i]][a[i]];
        if(!flag) printf("-1\n");
        else printf("%I64d\n", ans);
    }
     return 0;
}