There is a famous joke-riddle for children:
Three turtles are crawling along a road. One turtle says: ``There are two turtles ahead of me.'' The other turtle says: ``There are two turtles behind me.'' The third turtle says: ``There are two turtles ahead of me and two turtles behind me.'' How could this have happened? The answer is -- the third turtle is lying!
Now in this problem you have n turtles crawling along a road. Some
of them are crawling in a group, so that they do not see members of
their group neither ahead nor behind them. Each turtle makes a statement
of the form: ``There are ai turtles crawling ahead of me and
bi turtles crawling behind me.'' Your task is to find the
minimal number of turtles that must be lying.
Let us formalize this task. Turtle i has xi coordinate.
Some turtles may have the same coordinate.
Turtle i tells the truth if and only if ai is the number of turtles
such that xj > xi and bi is the number of turtles such that
xj < xi. Otherwise, turtle i is lying.
The input contains several test cases. The first line of each case consists of a integer number n.
It is followed by n lines containing numbers a_i and b_i that describe statements of each turtle for i from 1 to n.
For each input case, print one output line containing an integer number m -- the minimal
number of turtles that must be lying.
3 2 0 0 2 2 2 5 0 2 0 3 2 1 1 2 4 0
1 2
Migrated from old NTUJ.
NEERC 2004
| No. | Testdata Range | Score |
|---|