#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int T,n;
struct node{
    int x,y;
    bool operator <(const node b)const{return x<b.x;}
}p[30];
int main(){
    scanf("%d",&T);
    for (int i=1; i<=T; i++){
        scanf("%d",&n); int cnt=0; long long ans=0;
        for (int j=1; j<=n; j++) scanf("%d%d",&p[j].x,&p[j].y);
        sort(p+1,p+1+n);
        for (int j=n; j>=1; j--)
            for (int k=1; k<=p[j].y; k++){
                cnt+=p[j].x;
                if (cnt>=0) ans+=cnt;
            }
                
        printf("%lld\n",ans);
    }
    return 0;
}