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.
n = int(input())
c = 0;dif = -10
for i in range(n) :
    a,b = map(int,input().split())
    if(abs(a-b)>dif) :
        dif = b-a
        key = i+1
    if(b>=a) :
        c += 1
if(c==n) :
    print(0)
else :
    print(key)