#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
typedef long long ll;
const int M=2010;
int n,m,i,j,k,a[100010],b[100010],c[M],w[M],dp[M][11];
int main(){
    while (scanf("%d%d",&n,&m)!=EOF){
        for (i=1;i<=n;i++)scanf("%d%d",&a[i],&b[i]);
        for (i=1;i<=m;i++)scanf("%d%d",&w[i],&c[i]);
        for (i=0;i<=10;i++)dp[0][i]=0;
        for (i=1;i<=2000;i++)
            for (j=0;j<=10;j++)dp[i][j]=1<<30;
        for (i=1;i<=m;i++)
            for (j=0;j<=10&&j<=c[i];j++)
                for (k=0;k<=1000;k++)
                    dp[k+c[i]-j][j]=min(dp[k+c[i]-j][j],dp[k][j]+w[i]);
        for (i=1999;i;i--)
            for (j=0;j<=10;j++)
                dp[i][j]=min(dp[i][j],dp[i+1][j]);
        ll ans=0;
        for (i=1;i<=n;i++){
            if (dp[a[i]][b[i]]==1<<30){ans=-1;break;}
            ans+=dp[a[i]][b[i]];
        }
        printf("%I64d\n",ans);
    }
}