//Δ_1003
#include<iostream>
#include<cstdio>
#include<fstream>
#include<algorithm>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<bitset>
#include<cmath>
#include<cstring>
#include<cstdlib>
using namespace std;
typedef long long LL;
typedef double DB;
const int N = 111111;
const int A = 1111;
const int B = 11;
const int inf = 1e9;
void cmin(int&x,int y){
    if(x>y)
        x=y;
}
int n,m,a[N],b[N],f[A*2][B];
int main()
{
    int i,o,k,p;
    LL s;
    while(cin>>n>>m){
        for(o=0;o<B;o=o+1){
            for(i=1;i<A*2;i=i+1)
                f[i][o]=inf;
            f[0][o]=0;
        }
        for(i=1;i<=n;i=i+1)
            cin>>a[i]>>b[i];
        while(m--){
            cin>>k>>p;
            for(o=0;o<B&&o<p;o=o+1)
                for(i=p-o;i<A*2;i=i+1)
                    cmin(f[i][o],f[i-(p-o)][o]+k);
        }
        for(o=0;o<B;o=o+1)
            for(i=A*2-1;i>=1;i=i-1)
                cmin(f[i-1][o],f[i][o]);
        s=0;
        p=0;
        for(i=1;i<=n;i=i+1){
            k=f[a[i]][b[i]];
            if(k>=inf)
                p=1;
            s+=k;
        }
        if(p)
            s=-1;
        cout<<s<<endl;
    }
    return 0;
}