Number of toys

Input

The first line contains an integer n~(0 \le n \le 1000) — the number of toy types in the price list. Each of the following $n$ lines contains two integers:

• a~(0 \le a \le 1000) — the number of toys of this type, and

• b~(0 < b \le 10000) — the price of one toy of this type, in hryvnias.

Output

Print the total number of toys with a price less than $50$ hryvnias.

Examples