#include <iostream>
#include<algorithm>
#include<cstdio>
using namespace std;
typedef long long ll;
int k[1005],p[1005],a[100005],b[100005];
ll dp[1005][12];
const int inf=1e9+7;
inline void read(int &x)
{
    x=0;char p=getchar();
    while(!(p<='9'&&p>='0'))p=getchar();
    while(p<='9'&&p>='0') x*=10,x+=p-48,p=getchar();
}
int main()
{
    int n,m;
    while(~scanf("%d%d",&n,&m))
    {
        int mb=0,ma=0;
        for(int i=1;i<=n;i++)
         {
            read(a[i]);read(b[i]);
            mb=max(mb,b[i]);
            ma=max(ma,a[i]);
         }
        for(int i=1;i<=m;i++) { read(k[i]); read(p[i]);}
         for(int i=0;i<=mb;i++)
         {
             dp[0][i]=0;
             for(int j=1;j<=ma;j++)
             {
                dp[j][i]=inf;
                for(int q=1;q<=m;q++)
                {
                   if(p[q]<=i) continue;
                   int t=j-p[q]+i;
                   if(t<0) t=0;
                   dp[j][i]=min(dp[j][i],dp[t][i]+k[q]);
                }
             }
         }
         ll ans=0;
         for(int i=1;i<=n;i++)
            if(dp[a[i]][b[i]]==inf)
             { ans=-1;break; }
            else ans +=dp[a[i]][b[i]];
        printf("%I64d\n",ans);
    }
    return 0;
}