#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define max_n 100010
#define INF 0x3f3f3f3f
using  namespace std;
typedef long long LL;
LL dp[1005][12];
LL a[max_n], b[max_n], k[max_n], p[max_n];
 
int main() {
    LL p1, p2, n, m;
    while(scanf("%lld %lld", &n, &m) != EOF) {
        LL maxn1 = 0, maxn2 = 0;
        for(LL i = 0; i < n; i++) {
            scanf("%lld %lld", &a[i], &b[i]);
            maxn1 = max(maxn1, b[i]);
        }
        for(LL i = 0; i < m; i++) {
            scanf("%lld %lld", &k[i], &p[i]);
            maxn2 = max(maxn2, p[i]);
        }
        if(maxn2 <= maxn1) {   //特判一下，最大攻击值不大于防御值 
            printf("-1\n");
            continue;
        }
        memset(dp, INF, sizeof(dp));
        for(LL i = 0; i <= 10; i++) {
            for(LL v = 1; v < 1005; v++) {  //枚举血量 
                for(LL j = 0; j < m; j++) { //枚举攻击值，处理成完全背包 
                    LL res = p[j] - i;
                    if(res <= 0) continue;
                    if(res >= v) dp[v][i] = min(dp[v][i], k[j]); //分情况 
                    else dp[v][i] = min(dp[v][i], dp[v - res][i] + k[j]);
                }
            }
        }
        LL ans = 0;
        for(LL i = 0; i < n; i++) {
            ans += dp[a[i]][b[i]];
        }
        printf("%lld\n", ans);
    }
    return 0;
}