#include <algorithm>
#include <iostream>
#include <sstream>
#include <cstring>
#include <cstdlib>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <queue>
#include <stack>
#include <ctime>
#include <map>
#include <set>
using namespace std;
#define INF 0x3f3f3f3f
typedef long long LL;
const int N=100005;
const int mod=1e9+7;

LL a[N],b[N];
LL p[1005],k[1005];

LL dp[1005][15];

int main() {
    int n,m;
    while (cin>>n>>m) {
        LL att,def,hp;
        att=def=hp=0;
        for (int i=1; i<=n; i++) {
            scanf("%I64d %I64d",&a[i],&b[i]);
            def=max(def, b[i]);
            hp=max(a[i], hp);
        }
        for (int i=1; i<=m; i++) {
            scanf("%I64d %I64d",&k[i],&p[i]);
            att=max(att, p[i]);
        }
        
        if (def>=att) {
            cout<<"-1"<<endl;
            continue;
        }
        
        memset(dp, 0, sizeof(dp));
        for (int i=0; i<=10; i++) {
            for (int j=1; j<=hp; j++) {
                dp[j][i]=INF;
                for (int u=1; u<=m; u++) {
                    int dmg=p[u]-i;
                    if (dmg<0) {
                        continue;
                    }
                    if (dmg<j) {
                        dp[j][i]=min(dp[j][i],dp[j-dmg][i]+k[u]);
                    } else {
                        dp[j][i]=min(dp[j][i],k[u]);
                    }
                }
            }
        }
        LL ans=0;
        for (int i=1; i<=n; i++) {
            ans+=dp[a[i]][b[i]];
        }
        cout<<ans<<endl;
    }
}