1 /**************************************************************
  2     Problem: 3280
  3     User: Tunix
  4     Language: C++
  5     Result: Accepted
  6     Time:276 ms
  7     Memory:5972 kb
  8 ****************************************************************/
  9  
 10 //BZOJ 3280
 11 #include<vector>
 12 #include<cstdio>
 13 #include<cstring>
 14 #include<cstdlib>
 15 #include<iostream>
 16 #include<algorithm>
 17 #define rep(i,n) for(int i=0;i<n;++i)
 18 #define F(i,j,n) for(int i=j;i<=n;++i)
 19 #define D(i,j,n) for(int i=j;i>=n;--i)
 20 #define pb push_back
 21 using namespace std;
 22 inline int getint(){
 23     int v=0,sign=1; char ch=getchar();
 24     while(ch<‘0‘||ch>‘9‘){ if (ch==‘-‘) sign=-1; ch=getchar();}
 25     while(ch>=‘0‘&&ch<=‘9‘){ v=v*10+ch-‘0‘; ch=getchar();}
 26     return v*sign;
 27 }
 28 const int N=510,M=200000,INF=~0u>>2;
 29 typedef long long LL;
 30 /******************tamplate*********************/
 31 int n,m,k,ans,tot,flow;
 32 struct edge{int from,to,v,c;};
 33 struct Net{
 34     edge E[M];
 35     int head[N],next[M],cnt;
 36     void ins(int x,int y,int z,int c){
 37         E[++cnt]=(edge){x,y,z,c};
 38         next[cnt]=head[x]; head[x]=cnt;
 39     }
 40     void add(int x,int y,int z,int c){
 41         ins(x,y,z,c); ins(y,x,0,-c);
 42     }
 43     int from[N],Q[M],d[N],S,T,ss;
 44     bool inq[N];
 45     bool spfa(){
 46         int l=0,r=-1;
 47         F(i,1,T) d[i]=INF;
 48         d[S]=0; Q[++r]=S; inq[S]=1;
 49         while(l<=r){
 50             int x=Q[l++];
 51             inq[x]=0;
 52             for(int i=head[x];i;i=next[i])
 53                 if(E[i].v>0 && d[x]+E[i].c<d[E[i].to]){
 54                     d[E[i].to]=d[x]+E[i].c;
 55                     from[E[i].to]=i;
 56                     if (!inq[E[i].to]){
 57                         Q[++r]=E[i].to;
 58                         inq[E[i].to]=1;
 59                     }
 60                 }
 61         }
 62         return d[T]!=INF;
 63     }
 64     void mcf(){
 65         int x=INF;
 66         for(int i=from[T];i;i=from[E[i].from])
 67             x=min(x,E[i].v);
 68         for(int i=from[T];i;i=from[E[i].from]){
 69             E[i].v-=x;
 70             E[i^1].v+=x;
 71         }
 72         flow+=x;
 73         ans+=x*d[T];
 74     }
 75     void init(){
 76         n=getint(); m=getint(); k=getint();
 77         flow=tot=ans=0; cnt=1; memset(head,0,sizeof head);
 78         S=0; ss=n+n+1; T=n+n+2;
 79         int x,y,z;
 80         F(i,1,n){
 81             x=getint(); tot+=x;
 82             add(S,i,x,0);
 83             if (i<n) add(i,i+1,INF,0);
 84             add(ss,i+n,INF,0);
 85             add(i+n,T,x,0);
 86         }
 87         F(i,1,m){
 88             x=getint(); y=getint();
 89             add(S,ss,x,y);
 90         }
 91         F(i,1,k){
 92             x=getint(); y=getint();
 93             F(j,1,n) if(j+x+1<=n) add(j,j+n+x+1,INF,y);
 94             else break;
 95         }
 96         while(spfa()) mcf();
 97         if (flow==tot) printf("%d\n",ans);
 98         else puts("impossible");
 99     }
100 }G1;
101  
102 int main(){
103 #ifndef ONLINE_JUDGE
104     freopen("3280.in","r",stdin);
105     freopen("3280.out","w",stdout);
106 #endif
107     int T=getint();
108     F(i,1,T){
109         printf("Case %d: ",i);
110         G1.init();
111     }
112     return 0;
113 }