#include<bits/stdc++.h>
//#pragma GCC optimize("Ofast")
using namespace std;
template<typename T>
inline bool cmax(T&x,const T& y){return x<y?x=y,1:0;}
template<typename T>
inline bool cmin(T&x,const T& y){return y<x?x=y,1:0;}
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<vector<int> > vii; 
typedef unsigned long long ull;
#define sz(x) (int(x.size()))
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define eb emplace_back
#define em emplace
#define X first
#define Y second
const int mod=998244353;
inline void MOD(int&x){x-=mod,x+=x>>31&mod;}
inline void MOD(ll& x){x-=mod,x+=x>>63&mod;}
inline int add(int x,int y){MOD(x+=y);return x;}
inline int mul(int x,int y){return 1ll*x*y%mod;}
template<typename ... A>inline int mul(const int& x,const A&... p){return 1ll*x*mul(p...)%mod;}
inline ll ksm(ll a,ll p=mod-2){ll ans=1;for(;p;p>>=1,a=a*a%mod)if(p&1)ans=ans*a%mod;return ans;}
typedef long double LD;
const int MAXN=5e5+10;
inline void solve()
{
    int n;cin>>n;
    vector<pii> a(n+1);
    for(int i=1;i<=n;i++)cin>>a[i].first>>a[i].second;
    sort(a.begin()+1,a.end());
    int l=1,r=n;
    ll ans=0;
    while(l<r)
    {
        if(a[l].second<a[r].second)
        {
            ans+=1ll*a[l].second*(a[r].first-a[l].first);
            a[r].second-=a[l].second;l++;
        }
        else
        {
            ans+=1ll*a[r].second*(a[r].first-a[l].first);
            a[l].second-=a[r].second;r--;
        }
    }
    cout<<ans<<'\n';

}
int main()
{
    
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);cout<<fixed<<setprecision(10);
	int T;cin>>T;while(T--)solve();
	return 0;
}