Problem G: noip2016 买铅笔

Problem G: noip2016 买铅笔

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 29  Solved: 16
[Status] [Submit] [Creator:]

Description

Sample Input Copy 

57
2 2
50 30
30 27

Sample Output Copy 

54

HINT

[Submit][Status]