You are given the number of kinds of the toys in the shop, the number of toys of each kind and cost of a toy of each kind. Find the number of toys with cost less than 50 grn.

Input

The first line contains the number of kinds of the toys n (0 ≤ n ≤ 1000). Each of the next n lines contains 2 numbers: the number of toys a (0 ≤ a ≤ 1000) of the next kind and their price b (0 < b ≤ 10000) in grn.

Output

Print the number of toys with cost less than 50 grn.