#include<stdio.h>
#include<string.h>
#include<iostream>
using namespace std;
typedef  long long LL;
const int INF = 0x3f3f3f3f;
const int maxn=100000+5;
const int maxm=1000+5;
 
int a[maxn],b[maxn];
int k[maxm],p[maxm];
LL dp[maxn][20];//血量为i,防御为j,消耗的最少晶石
 
int max(int a,int b){
    return a>b?a:b;
}
int min(int a,int b){
    return a<b?a:b;
}
 
int main(){
    int n,m;
    while(cin>>n>>m){
    
        int mhp = 0; //怪物最大hp
        int mf = 0; //怪物最大防御
        int mg = 0; //最大攻击 
        int i,j;
        for( i=0;i<n;i++){
            scanf("%d%d",&a[i],&b[i]);
            mf = max(mf,b[i]);
            mhp = max(mhp,a[i]);
        }
        for( j=0;j<m;j++){
            scanf("%d%d",&k[j],&p[j]);
            mg = max(mg,p[j]);
        }
        if(mg<=mf){
            printf("-1\n");
            continue;
        }
        memset(dp,INF,sizeof(dp));
        for( j=0;j<=10;j++){     //防御值
            for( i=1;i<=mhp;i++){ //血量值
                for(int z=0;z<m;z++){//第z个技能
                    if(p[z]<=j) continue;
                    else if(i<=p[z]-j)
                        dp[i][j] = min(dp[i][j],k[z]);  
                    else
                        dp[i][j] = min(dp[i][j],dp[i-(p[z]-j)][j]+k[z]); 
                }
            }
        }
        LL res = 0;
        for( i=0;i<n;i++){
            res +=dp[a[i]][b[i]];
        }
        printf("%I64d\n",res);
    }
 
    return 0;
}