#include<bits/stdc++.h>
using namespace std;
__int64 dp[1005][11],num[1005][11],sum;
int sk[1005];
struct node
{
    int k,p;
}q[1005];
int main()
{
        int n,m,i,j,l,a,b,len;
        while(~scanf("%d%d",&n,&m)){
                memset(dp,0,sizeof(dp));
                memset(num,0,sizeof(num));
                memset(sk,0,sizeof(sk));
                int min_b=15,max_a=0,max_b=0,max_p=0;
                for(i=0;i<n;i++){
                        scanf("%d%d",&a,&b);
                        num[a][b]++;
                        min_b=min(min_b,b);
                        max_a=max(max_a,a);
                        max_b=max(max_b,b);
                }
                len=0;
                while(m--){
                        scanf("%d%d",&a,&b);
                        if(b<=min_b) continue;
                        if(sk[b]&&sk[b]<=a) continue;
                        sk[b]=a;
                        q[len].k=a;q[len++].p=b;
                        max_p=max(max_p,b);
                }
                m=len;
                if(max_p<=max_b){
                        puts("-1");
                        continue;
                }
                for(l=0;l<=10;l++){
                        for(i=1;i<=max_a;i++){
                                __int64 cnt=-1;
                                for(j=0;j<m;j++){
                                        int op=q[j].p-l;
                                        if(op<=0)continue;
                                        if(i-op<=0){
                                                if(cnt==-1||cnt>q[j].k) cnt=q[j].k;
                                                continue;
                                        }
                                        if(cnt==-1||cnt>dp[i-op][l]+q[j].k) cnt=dp[i-op][l]+q[j].k;
                                }
                                dp[i][l]=cnt;
                        }
                }
                sum=0;
                for(i=1;i<=max_a;i++) for(j=0;j<=10;j++) sum+=dp[i][j]*num[i][j];
                printf("%I64d\n",sum);
        }
        return 0;
}