Bestcoder 1st Anniversary ($) 1001 Souvenir

Souveniraccepts:901submissions:2743Time limit:2000/1000 MS (java/others)Memory limit:262144/262144 K (java/others)Problem Description

Today is the 1st anniversary of Bestcoder. Soda, the contest manager, wants to buy a souvenir for each contestant. You can buy the souvenir one by one or set by set in the shop. The price of a souvenir isp p yuan and the price for a set of souvenirs if& nbsp q q yuan. There ' S m< Span class= "Strut bottom" >m souvenirs in one Set.

There ' s nN contestants in the contest today. Soda wants to know the minimum cost needed to buy a souvenir for each contestant.

Input

There is multiple test cases. The first line of input contains an integerTT   (1 \le T \le 10^5) (1≤t≤1 0 ? 5 ??

There ' s a line containing 4 integersN, M, p, qN,M,P,Q(1 \le N, M, p, Q \le 10^4)(1≤n,m,p,q≤10? ) 4?? ).

Output

For each test case, the output of the minimum cost needed.

Sample Input

21 2 2 11 2 3 4

Sample Output

13

Hintfor The first case, Soda can use 1 yuan to buy a set of 2 souvenirs. For the second case, Soda can use 3 yuan to buy a souvenir.

1#include <stdio.h>2#include <string.h>3#include <algorithm>4 using namespacestd;5 intMain ()6 {7     intt,n,m,p,q,i,j,k;8scanf"%d",&T);9      while(t--)Ten     { Onescanf"%d %d%d%d",&n,&m,&p,&q); A         if((Double) p<= (Double) q/m) -         { -printf"%d\n"Np); the         } -         Else -         { -             intx=0; +              for(i=1;; i++) -             { +x=x+m; A                 if(x>=N) at                      Break; -             } -printf"%d\n", Min (I*q, (i-1) *q+ (n (x-m)) *p)); -         } -     } -     return 0; in}

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Bestcoder 1st Anniversary ($) 1001 Souvenir