#include<iostream>
#include<string>
using namespace std;
#define min(a,b) a<b?a:b
int w[501],p[501];
int f[100001];
int main()
{
int t,i,j,n,a,b,MAX;
freopen("D:\\input.txt","r",stdin);
cin>>t;
while(t--)
{
cin>>a>>b;
MAX=b-a;
cin>>n;
for(i=0;i<n;i++)
{
cin>>p[i]>>w[i];
}
for(i=0;i<=100000;i++)
{
f[i]=1000000;
}
f[0]=0;
for(i=0;i<n;i++)
{
for(j=w[i];j<=MAX;j++)
{
f[j]=min(f[j],f[j-w[i]]+p[i]);
}
}
if(f[MAX]<1000000)
{
cout<<"The minimum amount of money in the piggy-bank is "<<f[MAX]<<'.'<<endl;
}
else
cout<<"This is impossible."<<endl;
}
return 0;
}