text: #include <iostream>
  
  using namespace std;
  
  int main()
  {
      int a,b,c,d,sum=0;
  
      while(cin>>a>>b)
      {
          if(a>b)
          {
              if(b%2==0)
              {
                  c=b;
                  if(a%2==0)
                  {
                       d=a;
                  }
                  else
                  {
                      d=a-1;
                  }
              }
              else
              {
                  c=b+1;
                  if(a%2==0)
                  {
                    d=a;
                  }
                  else{
                    d=a-1;
                  }
              }
              sum=0;
              for(int x=c;x<=d;x=x+2)
              {
                  sum+=x;
              }
          }
          else
          {
            if(b%2==0)
              {
                  c=b;
                  if(a%2==0)
                  {
                       d=a;
                  }
                  else
                  {
                      d=a+1;
                  }
              }
              else
              {
                  c=b-1;
                  if(a%2==0)
                  {
                    d=a;
                  }
                  else{
                    d=a+1;
                  }
              }
              sum=0;
        for(int i=d;i<=c;i=i+2)
          {
              sum+=i;
          }
      }
  
        cout<<sum<<endl;
      }
      return 0;
  }
  