#include <cstdio>

 #include <algorithm>

 #include <cstring>

 #include <cmath>

 #include <map>

 #include <iterator>

 #include <vector>

 using namespace std;

 typedef long long LL;

 int T;

 int E,F;

 int dp[];

 int p[],w[];

 const int INF = ;

 int main(){

     scanf("%d",&T);

     while( T-- ){

         scanf("%d%d",&E,&F);

         F -= E;

         int n;

         scanf("%d",&n);

         for(int i=;i<;i++) dp[i] = INF;

         dp[] = ;

         for(int i=;i<=n;i++) scanf("%d%d",&p[i],&w[i]);

         for(int i=;i<=n;i++){

             for(int j=w[i];j<=F;j++){

                 dp[j] = min(dp[j],dp[j-w[i]]+p[i]);

             }

         }

         if( dp[F]!=INF )

             printf("The minimum amount of money in the piggy-bank is %d.\n",dp[F]);

         else

             puts("This is impossible.");

     }

     return ;

 }