Problem Description

Victor has a machine. When the machine starts up, it will pop out a ball immediately. After that, the machine will pop out a ball every

 w seconds. However, the machine has some flaws, every time after x seconds of process the machine has to turn off for y seconds for maintenance work. At the second the machine will be shut down, it may pop out a ball. And while it's off, the machine will pop out no ball before the machine restart.

Now, at the 0 second, the machine opens for the first time. Victor wants to know when the n-th ball will be popped out. Could you tell him?

 

 

Input

The input contains several test cases, at most

 100 cases.

Each line has four integers x, y, w and n. Their meanings are shown above。

1≤x,y,w,n≤100.

 

 

Output

For each test case, you should output a line contains a number indicates the time when the

 n-th ball will be popped out.

 

 

Sample Input

2 3 3 3

98 76 54 32

10 9 8 100

 

 

Sample Output

10

2664

939

  题意：一台机器每W分钟吐出一个球，但是它每隔x分要停y分钟。它每次开始时要吐出一个球。求吐出第n个球的时间。

 我们先算每x分钟能吐出多少个球，用n除每分钟吐出的球，就能知道机器要停机次，然后就简单了。

  

1 #include
     
       2 #include
      
        3 using namespace std; 4 int main() 5 { 6     int n,w,x,y,ans,t; 7     while (~scanf("%d%d%d%d",&x,&y,&w,&n)) 8     { 9         t=x/w+1;10         if (n%t==0)11         {12             ans=(n/t-1)*(x+y);13             ans+=(t-1)*w;14         }15         else16         {17             ans=(n/t)*(x+y);18             ans+=(n%t-1)*w;19         }20         printf("%d\n",ans);21     }22 }