#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cmath>
using namespace std;
int a[100010] , b[100010];
int k[1010] , p[1010];
int kp[11][1010];
int dp[2010];
int main()
{
    int n , m;
    while( scanf( "%d %d" , &n , &m ) != EOF )
    {
        for( int i=0 ; i<n ; i++ ) scanf( "%d %d" , &a[i] , &b[i] );
        for( int i=0 ; i<m ; i++ ) scanf( "%d %d" , &k[i] , &p[i] );
        int maxa = 0, maxb = 0 , maxp = 0;
        for( int i=0 ; i<n ; i++ )
        {
            maxa = max( maxa , a[i] );
            maxb = max( maxb , b[i] );
        }
        for( int i=0 ; i<m ; i++ ) maxp = max( maxp , p[i] );
        if( maxb >= maxp )
        {
            printf( "-1\n" );
            continue;
        }
        for( int D = 0 ; D <= maxb ; D++ )
        {
            memset( dp , -1 , sizeof(dp) );
            dp[0] = 0;
            int mx = 0;
            for( int i=0 ; i<maxa ; i++ )
                if( dp[i] >= 0 )
                {
                    for( int j=0 ; j<m ; j++ )
                        if( D < p[j] )
                        {
                            int nxt = i + p[j] - D;
                            if( dp[nxt] < 0 || dp[nxt] > dp[i] + k[j] )
                            {
                                dp[nxt] = dp[i] + k[j];
                                mx = nxt;
                            }
                        }
                }
            for( int i=mx-1 ; i>0 ; i-- )
            {
                if( dp[i] >= 0 ) dp[i] = min( dp[i] , dp[i+1] );
                else dp[i] = dp[i+1];
            }
            for( int i=0 ; i<=maxa ; i++ ) kp[D][i] = dp[i];
        }
        long long ans = 0;
        for( int i=0 ; i<n ; i++ ) ans += (long long)kp[ b[i] ][ a[i] ];
        printf( "%I64d\n" , ans );
    }
    return 0;
}