#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<vector>
using namespace std;
int val[5000];
int main()
{
    int T;
    scanf("%d",&T);
    while(T--){
        int n;
        scanf("%d",&n);
        int z=0,f=0;
        int cnt=0;
        for(int i=1;i<=n;++i){
            int a,b;
            scanf("%d %d",&a,&b);
            for(int j=0;j<b;++j){
                val[cnt++]=a;
            }
            if(a>=0){
                z+=a*b;
            } else {
                f+=a*b;
            }
        }
        long long ans=0;
        sort(val,val+cnt);
        int start=0;
        while(z<abs(f)){
            f-=val[start];
            start++;
        }
        for(int i=start,j=1;i<cnt;++i,++j){
            ans+=j*val[i];
        }
        printf("%I64d\n",ans);
    }
    return 0;
}