#include <iostream>

#include <stdio.h>

using namespace std;



int main()

{

int t,e,f,p[501],w[501],n,k[10001],fe;

cin>>t;

while(t--)

{

cin>>e>>f>>n;

fe = f - e;

for(int i = 0; i < n ; i++)

{

cin>>p[i]>>w[i];

}

k[0] = 0;

for(int i = 1 ; i <= fe;i++)

{

k[i] = 50000000;

}

for(int i = 0 ; i < n ; i++)

{

for(int m = w[i] ; m <= fe;m++)

{

if(k[m-w[i]]+p[i]<k[m])

k[m] = k[m-w[i]] + p[i];

}

}

if(k[fe] == 50000000)

printf("This is impossible.\n");

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

}

return 0;

}