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. \InputFile The first line contains the number of kinds of the toys $n~(0 \le n \le 1000)$. Each of the next $n$ lines contains two numbers: the number of toys $a~(0 \le a \le 1000)$ of the next kind and their price $b~(0 < b \le 10000)$ in grn. \OutputFile Print the number of toys with cost less than $50$ grn.