#include<cstdio>
#include<algorithm>
#include<cstring>
#define rep(i,a,b) for(int i=a;i<=b;i++)
using namespace std;
const int N=1e5+5,M=1005;
int a[N],b[N],k[M],p[M],n,m,maxhp,max1,max2;
long long ans;
int dp[11][M];//DEF,伤害(no less than)
void clear(){
    max1=maxhp=max2=0;
    ans=0l;
    memset(dp,0x3f,sizeof(dp));
}
int main(){
    while(scanf("%d%d",&n,&m)!=EOF){
        clear();
        rep(i,1,n){
            scanf("%d%d",a+i,b+i);        
            max1=max(b[i],max1);
            maxhp=max(a[i],maxhp);
        }
        rep(i,1,m){
            scanf("%d%d",k+i,p+i);
            max2=max(p[i],max2);
        }
        if(max1>=max2){//特判 
            printf("-1\n");
            continue;
        }
        rep(def,0,max1){
            dp[def][0]=0;
            rep(i,1,maxhp){//消耗血量
                rep(j,1,m){//j技能
                    if(p[j]<=def) continue;
                    dp[def][i]=min(dp[def][max(i-p[j]+def,0)]+k[j],dp[def][i]); 
                }
            }
        }
        rep(i,1,n)
            ans+=dp[b[i]][a[i]];
        printf("%lld\n",ans);
    }
    return 0;
}