#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<set>
#include<map>
#include<ext/pb_ds/priority_queue.hpp>  
#include<queue>
#include<stack>
#define pointtype double
#define pointtype_INT 0
using namespace std;
typedef long long LL;
typedef pair<int,int>pii;
typedef unsigned uint;
typedef unsigned long long uLL;
const double pi=acos(-1);
template<class T>
void Read(T &x){
    char c;
    bool f(0);
    while(c=getchar(),c!=EOF){
        if(c=='-')
            f=1;
        else if(c>='0'&&c<='9'){
            x=c-'0';
            while(c=getchar(),c>='0'&&c<='9')
                x=x*10+c-'0';
            ungetc(c,stdin);
            if(f)
                x=-x;
            return;
        }
    }
}
struct point{
    pointtype x,y;
    inline point(){
    }
    inline point(pointtype x,pointtype y):x(x),y(y){
    }
    inline point operator-(const point &a)const{
        return point(x-a.x,y-a.y);
    }
    #if pointtype_INT==1
        inline point operator*(const point &a)const{
            return point(1ll*x*a.x-1ll*y*a.y,1ll*x*a.y+1ll*y*a.x);
        }
        inline friend LL cross(const point &a,const point &b){
            return 1ll*a.x*b.y-1ll*a.y*b.x;
        }
        inline friend LL dot(const point &a,const point &b){
            return 1ll*a.x*b.x+1ll*a.y*b.y;
        }
    #else
        inline point operator*(const point &a)const{
            return point(x*a.x-y*a.y,x*a.y+y*a.x);
        }
        inline friend pointtype cross(const point &a,const point &b){
            return a.x*b.y-a.y*b.x;
        }
        inline friend pointtype dot(const point &a,const point &b){
            return a.x*b.x+a.y*b.y;
        }
    #endif
};
int T,n;
vector<int>a;
long long sum,ans;
int main()
{
    Read(T);
    while(T--){
        a.clear();
        Read(n);
        int x,y;
        for(int i=1;i<=n;i++){
            sum=ans=0;
            Read(x),Read(y);
            while(y--)
                a.push_back(x);
        }
        sort(a.begin(),a.end(),greater<int>());
        sum=ans=0;
        for(auto j:a){
            sum+=j;
            if(sum<=0)
                break;
            ans+=sum;
        }
        printf("%I64d\n",ans);
    }
}