#include <iostream>#include <cstring>#include <cstdio>#include <cmath>#define inf 1e11#define LL long longusing namespace std;const int N=500;int map[N][N];int hp[N];int hshill[N];int ap[N];int ashill[N];int n,m;int edge[N][N];int cx[N];int cy[N];int mark[N];void builtmap(LL mid){ for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) { LL val=(LL)(mid-edge[i][j])*hp[i]+hshill[i]-mid*ap[j]-ashill[j]; if(val>=0)map[i][j]=1; }}int dfs(int u){ for(int v=1;v<=m;v++) { if(map[u][v]&&!mark[v]) { mark[v]=1; if(cy[v]==-1||dfs(cy[v])) { cx[u]=v; cy[v]=u; return 1; } } } return 0;}int maxmatch(){ int res=0; memset(cx,0xff,sizeof(cx)); memset(cy,0xff,sizeof(cy)); for(int i=1;i<=n;i++) { if(cx[i]==-1) { memset(mark,0,sizeof(mark)); res+=dfs(i); } } return res;}int main(){ while(scanf("%d%d",&n,&m)) { if(n==0&&m==0)break; for(int i=1;i<=n;i++) cin>>hshill[i]>>hp[i]; for(int j=1;j<=m;j++) cin>>ashill[j]>>ap[j]; for(int i=1;i<=n;i++) for(int j=1;j<=m;j++) cin>>edge[i][j]; LL lef=0,rig=inf,ans=-1; while(lef<=rig) { LL mid=(lef+rig)/2; memset(map,0,sizeof(map)); builtmap(mid); int tmp=maxmatch(); if(tmp==m) ans=mid,rig=mid-1; else lef=mid+1; } if(ans==-1) cout<<"IMPOSSIBLE"<<endl; else cout<<ans<<endl; } return 0;}
