//
//  main.cpp
//  baidu
//
//  Created by wch on 2017/8/5.
//  Copyright © 2017年 wch. All rights reserved.
//

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
using namespace std;

const long long INF = 1e9;


int main(){
    int n, m;
    int i, j, k;
    while(cin >> n >> m){
        vector<long long> vec_a(n), vec_b(n);
        vector<long long> vec_k(m), vec_p(m);
        long long max_a = -1;
        long long max_b = -1;
        long long max_p = -1;
        for(i=0; i<n; ++i){
            cin >> vec_a[i] >> vec_b[i];
            max_a = max(max_a, vec_a[i]);
            max_b = max(max_b, vec_b[i]);
        }
        
        for(i=0; i<m; ++i){
            cin >> vec_k[i] >> vec_p[i];
            max_p = max(max_p,vec_p[i]);
        }
        
        if(max_b >= max_p){
            cout << -1 << endl;
            continue;
        }
        
        vector<vector<long long> > dp(max_a+1, vector<long long>(11, INF));
        
        for(i=0; i<=10; ++i){
            dp[0][i] = 0;
        }
        
        for(i=0; i<=10; ++i){
            for(j=1; j<=max_a; ++j){
                for(k=0; k<m; ++k){
                    if(vec_p[k]-i >= j){
                        dp[j][i] = min(dp[j][i], vec_k[k]);
                    }
                    else if(vec_p[k]-i > 0){
                        dp[j][i] = min(dp[j][i], dp[j-(vec_p[k]-i)][i]+vec_k[k]);
                    }
                }
            }
        }
        
        long long ans = 0;
        for(i=0; i<n; ++i){
            ans += dp[vec_a[i]][vec_b[i]];
        }
        cout << ans << endl;
        
    }
    return 0;
}