codeforce - road to zero

#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fast()(ios_base::sync_with_stdio(0),cin.tie(NULL));
int main()
{
    fast();
    ll t ;
    cin>>t;
    while(t--)
    {
        ll x, y, a, b, mx, mn;
        cin>> x>>y>>a>>b;
        mn=min(x,y);
        mx=max(x,y);
        x=(mx-mn)*a+min(mn*b,2*mn*a);
        cout<<x<<endl;
    }
}