Vanya got an important task — he should enumerate books in the library and label each book with its number. Each of the *n* books should be assigned with a number from 1 to *n*. Naturally, distinct books should be assigned distinct numbers.

Vanya wants to know how many digits he will have to write down as he labels the books.
The first line contains integer *n* (1 ≤ *n* ≤ 10<sup class="upper-index">9</sup>) — the number of books in the library.
# coding=utf-8
t=int(input())
for i in range(t):
    s=0
    x=input().split()
    a=int(x[0])
    b=int(x[1])
    k=int(x[2])
    if k%2==0:
        s=(a-b)*(k//2)
    else:
        s=(a-b)*(k//2)+a
    print(s)
 	   	  			    	 	  	  		 	