Mock CCC '18 Contest 2 J3/S1 - An Array Problem

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Points: 7 (partial)
Time limit: 0.6s
Memory limit: 1G

Problem type
Allowed languages
Ada, Assembly, Awk, Brain****, C, C#, C++, COBOL, CommonLisp, D, Dart, F#, Forth, Fortran, Go, Groovy, Haskell, Intercal, Java, JS, Kotlin, Lisp, Lua, Nim, ObjC, OCaml, Octave, Pascal, Perl, PHP, Pike, Prolog, Python, Racket, Ruby, Rust, Scala, Scheme, Sed, Swift, TCL, Text, Turing, VB, Zig

You are given an array of N integers. A modification consists of selecting two distinct indices in the array that point to positive integers in the array and decreasing both integers by 1.

Compute the maximum number of modifications you can perform on the array until you can no longer perform any modifications.

Constraints

1 \le N \le 50

1 \le a_i \le 10^9

In tests worth 5 marks, the sum of all a_i will be less than or equal to 10^5.

Input Specification

The first line contains a single integer, N.

Each of the next N lines contains a single integer, a_1 through a_N in order.

Output Specification

Print, on a single line, the maximum number of modifications that can be performed.

Sample Input

3
1
2
1

Sample Output

2

Sample Input

5
1
2
1
10
3

Sample Output

7

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