#include <cstdio>
#include <algorithm>
using namespace std;
//#include <unordered_map>

typedef long long ll;
const int max_defend = 12;
const int max_val = 1010;
const int maxn = 100010;
const int INF = 1000000007;

int dp[max_defend][max_val];

int a[maxn], b[maxn];
int costs[maxn], vals[maxn];

void init(){
    //memset(dp, -1, sizeof(dp));
    for(int i = 0; i < max_defend; i++){
        dp[i][0] = 0;
        for(int j = 1; j < max_val; j++)
            dp[i][j] = INF;
    }
}

int main(){
   // freopen("in.txt", "r", stdin);
    int n, m;
    while(scanf("%d %d", &n, &m) != EOF){
        for(int i = 0; i < n; i++) scanf("%d %d", &a[i], &b[i]);
        init();
        int cost, val;
        for(int k = 0; k < m; k++){
            scanf("%d %d", &costs[k], &vals[k]);
        }
        for(int k = 0; k < m; k++){
            int cost = costs[k], val=vals[k];
            int upper = 10;
            if(val <= upper) upper = val - 1;
            for(int i = 0; i <= upper; i++){
                int delta = val - i;
                for(int j = 1; j <= delta; j++){
                    dp[i][j] = min(dp[i][j], cost);
                    //dp[i][j] = min(dp[i][j], dp[i][j-delta] + cost);
                }
                for(int j = delta+1; j < max_val; j++){
                    //if(j - delta <= 0) dp[i][j] = min(dp[i][j], cost);
                    dp[i][j] = min(dp[i][j], dp[i][j-delta] + cost);
                }
            }
        }
        bool ok = true;
        ll ans = 0;
        for(int i = 0; i < n; i++){
            if(dp[b[i]][a[i]] == INF) {
                ok = false;
                break;
            }
            ans += dp[b[i]][a[i]];
        }
        if(ok) printf("%lld\n", ans);
        else printf("-1\n");
    }
    return 0;
}