#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <iostream>
#include <string>
#include <cstring>
#include <algorithm>
#define LL __int64
using namespace std;
template<typename T>inline void read(T &x){
    x=0;bool f=false;char ch=getchar();
    while (ch<'0'||'9'<ch) {if(ch=='-') f=!f;ch=getchar();}
    while ('0'<=ch&&ch<='9') {x=x*10+ch-'0';ch=getchar();}
    if (f) x=-x;
}
inline void MAX(int &x,int y) {if (y>x) x=y;}
inline void MIN(LL &x,LL y) {if (y<x) x=y;}
inline void ADD(LL &x,LL y){x=x+y;}
const LL INF=0x3f3f3f3f3f3f3fLL;
const int maxn=1e5+10;
const int maxm=1e3+10;
int n,m,mxa,mxb,k[maxm],p[maxm],a[maxn],b[maxn];
LL dp[maxm],ans,cnt[maxm][20];

void init(int n){
    for (int i=0;i<=n;i++) dp[i]=INF;
    dp[0]=0LL;
}
int main(){
    while (~scanf("%d%d",&n,&m)){
        mxa=0;mxb=0;
        for (int i=0;i<n;i++){read(a[i]);read(b[i]);MAX(mxa,a[i]);MAX(mxb,b[i]);}
        for (int i=0;i<m;i++){read(k[i]);read(p[i]);}
        for (int l=0;l<=mxb;l++){
            init(mxa);
            for (int i=0;i<m;i++) if (p[i]>l)
                for (int j=0;j<=mxa;j++) MIN(dp[j],dp[max(0,j-p[i]+l)]+k[i]);
            for (int i=0;i<=mxa;i++) cnt[i][l]=dp[i];
        }
        ans=0LL;
        for (int i=0;i<n;i++) ADD(ans,cnt[a[i]][b[i]]);
        if (ans<INF) printf("%I64d\n",ans); else printf("-1\n");
    }
    return 0;
}