Fee Types and Total Cost

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

There are n fees, each with type m in {1,2,3} and nonnegative base x. Each fee costs m*x. Print the 64-bit total, or zero when empty.

Input

First n, followed by n pairs m x.

Output

Print the integer total with no currency symbol.

Subtasks

• Subtask 1 (20%): n ≤ 20, x ≤ 100.

• Subtask 2 (30%): n ≤ 1000, x ≤ 10^6.

• Subtask 3 (50%): n ≤ 100000, x ≤ 10^9.

Examples

Example 1

Input:

3
1 10
2 7
3 4

Output:

36

Explanation: The total is 10+14+12=36.

Example 2

Input:

0

Output:

0

Explanation: The empty set of fees costs zero.