D. Forming Teams (B)
time limit per test
0.5 seconds
memory limit per test
64 megabytes
input
standard input
output
standard output

Mr. Ahmad found that in some cases, it is impossible to satisfy everyone. Therefore, some individuals might be assigned to teams.

There are K PCs available at the IT labs, which may be prepared for 1, 2 or 3 students. Find the minimum possible number of unsatisfied students.

Input

The input contains 3 space-separated integers: N M K, where:

N is the number of students who don’t mind to participate individually or in a team of 2 or 3 members.

M is the number of students who chose to participate individually.

K is the number of available PCs in the IT Labs.

All integers are between 0 and 1,000,000,000 (inclusive).

Output

If K PCs are not enough to allow everyone to participate, print -1, otherwise print the minimum number of unsatisfied students.

Examples
Input
4 8 8
Output
2
Input
8 5 3
Output
-1
Input
6 3 6
Output
0