#include <bits/stdc++.h>

using namespace std;

typedef long long LL;
typedef pair<int,int> pp;


LL q[22][1000005];
int len[22];
LL k[10003];
LL p[10003];
LL dp[40003];
const LL INF=1e18;

int main()
{
    int n,m;
    while(scanf("%d %d",&n,&m)!=EOF)
    {
        memset(len,0,sizeof(len));
        int tank=0;
        LL life=0;
        for(int i=0 ; i<n ; i++)
        {
            int a,b;
            scanf("%d %d",&a,&b);
            q[b][len[b]]=a;
            len[b]++;
            tank=max(tank,b);
            life=max(life,(LL)a);
        }
        LL maxi=0;
        for(int i=0 ; i<m ; i++)
        {
            scanf("%I64d %I64d",&k[i],&p[i]);
            maxi=max(maxi,p[i]);
        }
        if(maxi<=tank)
        {
            printf("-1\n");
            continue;
        }
        LL ans=0;
        for(int def=0 ;def<=tank ; def++)
        {
            if(len[def]==0)
                continue;
            for(int i=1 ; i<=life ; i++)
            {
                dp[i]=INF;
            }
            dp[0]=0;
            for(int i=0 ; i<m ; i++)
            {
                if(p[i]<=def)
                {
                    continue;
                }
                LL re=p[i]-def;
                for(int j=0 ; j<=life ; j++)
                {
                    if(j<re)
                    {
                        dp[j]=min(dp[j],k[i]);
                    }
                    else
                    {
                        dp[j]=min(dp[j],dp[j-re]+k[i]);
                    }
                }
            }
            dp[0]=0;
            for(int i=0 ; i<len[def] ; i++)
            {
                ans+=dp[q[def][i]];
            }
        }
        printf("%I64d\n",ans);
    }
    return 0;
}