#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <cstring>
#define maxa 1005
#define maxn 100005
#define maxm 1005
#define INF 2000000005
#define maxb 15
#define LL long long int
using namespace std;
struct query{
    int a, b;
    query(int a, int b) : a(a), b(b){}
    query(){}
}q[maxn];
int n, m;
int cost[maxm];
int att[maxm];
int dp[maxa][maxb];
bool vis[maxa][maxb];
int def;
int DP(int res, int def){
    if (res <= 0) return 0;
    if (vis[res][def]) return dp[res][def];
    vis[res][def] = 1;
    int& ans = dp[res][def];
    ans = INF;
    for (int i = 1; i <= m; i++){
        if (att[i] <= def) continue;
        ans = min(ans, DP(res - att[i] + def, def) + cost[i]);
    }
    return ans;
}
int main(){
    while (scanf("%d%d", &n, &m) == 2){
        LL ans = 0;
        int maxatt = 0;
        int maxdef = 0;
        for (int i = 1; i <= n; i++){
            scanf("%d%d", &q[i].a, &q[i].b);
            maxdef = max(maxdef, q[i].b);
        }
        for (int i = 1; i <= m; i++){
            scanf("%d%d", &cost[i], &att[i]);
            maxatt = max(maxatt, att[i]);
        }
        if (maxdef >= maxatt){
            printf("-1\n");
            continue;
        }
        for (int i = 1; i <= n; i++){
            ans += DP(q[i].a, q[i].b);
        }
        memset(vis, 0, sizeof(vis));
        printf("%I64d\n", ans);
    }
    return 0;
}