Problem Statement

Today is Halloween, so Taro has decided to visit the houses in his neighborhood to get candy.

There are \(N\) houses in the neighborhood other than Taro's own.
Visiting house \(i\) gives him \(V_i\) pieces of candy, but
in order to distribute candy fairly among the neighborhood children,
if he already has \(T_i\) or more pieces of candy, he receives no candy at all.

Taro initially has no candy and can visit the neighborhood houses in any order he likes.
Find the maximum number of pieces of candy Taro can receive.
Each house can be visited only $1$ time.

Input

\(N\)
\(V_1\ T_1\)
\(V_2\ T_2\)
\(\dots\)
\(V_i\ T_i\)
\(\dots\)
\(V_N\ T_N\)

Line \(1\) contains an integer \(N\ (1 \leq N \leq 10000)\), the number of houses in the neighborhood.
Each of the following \(N\) lines contains, separated by a space, an integer \(V_i\ (1 \leq V_i \leq 10000)\), the number of pieces of candy received at house \(i\) \((1 \leq i \leq N)\), and
an integer \(T_i\ (1 \leq T_i \leq 10000)\), the threshold for receiving candy.

Output

Output the maximum number of pieces of candy Taro can receive.
Print a newline at the end.

Sample

3
1 1
3 2
5 3

6

5
1 1
1 4
1 2
1 5
1 3

5

7
2 1
2 3
9 2
3 1
6 4
3 5
4 8

11

2
1 3
100 2

101