Problem Statement

Yukio-kun and Yukime-san have decided to form a team and enter a competitive programming contest.
To prepare for the contest, the two trained desperately and acquired

• the ability to know exactly, the instant they glance at a problem statement, how many seconds each of them needs to solve the problem
• the ability to correctly solve any competitive programming problem within $10^3$ seconds

Now the contest has begun.
The contest the two are participating in this time has $N$ problems.
The moment the contest started, Yukio-kun and Yukime-san glanced at all $N$ problems and determined, for each problem $i$, the time $A_i$ (seconds) Yukio-kun takes to solve it and the time $B_i$ (seconds) Yukime-san takes to solve it.

• The two solve problems in parallel.
• One person does not solve multiple problems in parallel.
• The two do not solve the same problem at the same time.
• Each of them solves the problems assigned to them one after another, with no gaps in between.

$N$
$A_1$ $B_1$
$A_2$ $B_2$
$\vdots$
$A_N$ $B_N$

3
45 50
20 80
40 15

60

5
600 100
700 100
800 100
900 100
1000 100

500