#include <iostream>
using namespace std;
int main()
{
int t, n, a[26][2], x, y;
cin>>t;
for(int i = 0; i<t; i++)
{
cin>>n;
for(int j = 0; j<n; j++)
cin>>a[j][0]>>a[j][1];
for(int j = 0; j<(n - 1); j++)
{
for(int k = 0; k<(n - j - 1); k++)
{
if((a[k][0]>a[k + 1][0]) || (a[k][0] == a[k + 1][0] && a[k][1]>a[k + 1][1]))
{
x = a[k][0];
y = a[k][1];
a[k][0] = a[k + 1][0];
a[k][1] = a[k + 1][1];
a[k + 1][0] = x;
a[k + 1][1] = y;
}
}
}
long ans = 0, e = 1;
for(int j = 0; j<n; j++)
if(a[j][0]>0)
{
for(int k = 0; k<a[j][1]; k++)
{
ans = ans + e*a[j][0];
e++;
}
}
cout<<ans<<endl;
}
return 0;
}
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