#include<algorithm>
#include<iostream>
#include<cstring>
#include<fstream>
#include<bitset>
#include<cstdio>
#include<string>
#include<vector>
#include<cmath>
#include<queue>
#include<stack>
#include<map>
#include<set>
#define INF 0X3F3F3F3F
#define N 100010
#define M 2000100
#define LL long long
#define FF(i,a,b) for(int i=a;i<=b;++i)
#define RR(i,a,b) for(int i=a;i>=b;--i)
#define FJ(i,a,b) for(int i=a;i<b;++i)
#define SC(x) scanf("%d",&x)
#define SCC(x,y) scanf("%d%d",&x,&y)
#define SCCC(x,y,z) scanf("%d%d%d",&x,&y,&z)
#define SS(x) scanf("%s",x)
#define PR(x) printf("%d\n",x)
#define CL(a,b) memset(a,b,sizeof(a))
#define FD T&q=fd[rt],&ql=fd[rt<<1],&qr=fd[rt<<1|1]
#define MID int mid=((l+r)>>1)
#define lson rt<<1,l,mid
#define rson rt<<1|1,mid+1,r
#define zero(x) (((x)>0?(x):-(x))<EPS)
#define PB push_back
#define SZ size
#define PII pair<int,int>
#define PLL pair<long long,long long>
#define MP make_pair
#define IN freopen("in.txt","r",stdin)
#define OUT freopen("out.txt","w",stdout)
using namespace std;
const int MOD=1000000007;
const double PI=acos(-1.0);
const double EPS=1e-8;
//inline int II(){int n=0,ch=getchar();bool t=0;if(ch==-1)return 0;
//for(;ch<'0'||ch>'9';ch=getchar())if(ch=='-')t=1;
//for(;ch>='0'&&ch<='9';n=n*10+ch-'0',ch=getchar());if(t)return -n;return n;}
//inline void OO(int a){if(a<0){putchar('-');a=-a;}
//if(a>=10)OO(a/10);putchar(a%10+'0');}
//inline int sgn(double x){return(x>EPS)-(x<-EPS);}
//struct edge{int v,w,nx;}E[M*2+N*2];int head[N],EN;
//void init_edge(){EN=0;CL(head,-1);}
//void add_edge(int u,int v,int w){
//    E[EN]=(edge){v,w,head[u]};head[u]=EN++;
//    E[EN]=(edge){u,w,head[v]};head[v]=EN++;
//}
int ha[6000],hanum;
int f[6000],fnum;
int sum,n,x,y;
LL ans;
int main(){
  //  IN;
    int _;
    for(SC(_);_--;){
        sum=hanum=fnum=0;
        ans=0;SC(n);
        FF(i,1,n){
            SCC(x,y);
            if(x>0)sum+=x*y;
            if(x>=0){
                FF(j,1,y){
                    f[++fnum]=x;
                }
            }
            if(x<0){
                FF(j,1,y){
                    ha[++hanum]=-x;
                }
            }
        }
        sort(ha+1,ha+1+hanum);
        sort(f+1,f+1+fnum);
        FF(i,1,fnum){
            ans+=1LL*i*f[i];
        }
        int now=1;
        int tmp=0;
        for(;now<=hanum;++now){
            if((tmp+ha[now])<sum){
                tmp+=ha[now];
            }
            else break;
        }
        --now;
        LL ttt=0;
        RR(i,now,1){
            ttt+=1LL*(now-i+1)*(-1)*ha[i];
        }
        ans+=ttt;
        ans+=1LL*now*sum;
        printf("%I64d\n",ans);
    }
return 0;
}