PUCMM334 - White Hats

There are a number of people in a room (between 2 and 100), and each of them wears a hat which is either black or white. Every person counts the number of other people wearing white hats. You are given the number counted by each person. Print the total number of people wearing white hats, or -1 if count doesn't correspond to a valid situation.

Input

The first line is N, the number of persons.

Then N space separated integers follow, each one denoting the number of white hats each person sees.

Output

Print the total number of people wearing white hats, or -1 if count doesn't correspond to a valid situation.

Example

Input:                              Output:
3 2
2 1 1

Input:
Output:
3 3
2 2 2

Input:
Output:
2 0
0 0

Input: Output:
2 -1
10 10

Added by:Olson Ortiz
Date:2013-01-01
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM32-GCC MAWK BC C-CLANG NCSHARP CPP14 CPP14-CLANG COBOL COFFEE D-CLANG D-DMD DART ELIXIR FANTOM FORTH GOSU GRV JS-MONKEY JULIA KTLN NIM OBJC OBJC-CLANG OCT PICO PROLOG PYPY PYPY3 R RACKET RUST CHICKEN SQLITE SWIFT UNLAMBDA VB.NET
Resource:Olimpiada de ProgramaciĆ³n PUCMM ACM-ISC 2013

hide comments
2015-05-09 20:21:03 :.Mohib.:
Easy.....AC... :)
2015-02-12 15:52:02 ROHIT RAJ
similar to CRNVALEN :)
2014-02-26 21:12:16 /* EDWARD KENWAY */
there r some hidden/tricky cases for
o/p = -1
otherwise the problem is pretty straight forward
2014-01-31 21:17:07 parbays
@Doshi, check for the boundary cases.
one TC:
2
1 0
o/p: 1
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