1 #include <iostream>
 2 #include <cmath>
 3 using namespace std;
 4 int main()
 5 {
 6     double v,d;
 7     while(cin>>v>>d)
 8     {
 9         int x=int(v/d),i=1,j,t=0;
10         int n=x;
11         while(x-i>=0)
12         {
13             t=t+i;
14             x=x-i;
15             t+=1;
16             i++;
17         }
18         if(x>0)
19         {
20             t+=x;
21             if(abs(n-v/d)>0.00001)
22                 t++;
23         }
24         else
25         {
26             if(abs(n-v/d)>0.00001)
27                 t++;
28             else
29                 t--;
30         }    
31         cout<<t<<endl;
32     }
33 }