/+ dub.sdl:
    name "C"
    dependency "dcomp" version=">=0.7.4"
+/

import std.stdio, std.algorithm, std.range, std.conv;
// import dcomp.foundation, dcomp.scanner;

int main() {
    Scanner sc = new Scanner(stdin);
    int n; int[] a;
    sc.read(n);
    sc.read(a);
    bool[] ok = new bool[1<<24];
    ok[1] = true;
    foreach (d; a) {
        bool[] ok2 = new bool[1<<24];
        foreach (i, f; ok) {
            if (!f) continue;
            int x = d;
            if (!(i & (1<<x))) {
                ok2[i | (1<<x)] = true;
            }
            x = (24-d) % 24;
            if (!(i & (1<<x))) {
                ok2[i | (1<<x)] = true;
            }
        }
        ok = ok2;
    }
    int ans = 0;
    foreach (i, f; ok) {
        if (!f) continue;
//        writeln("debug ", i);
        int buf = 10000;
        foreach (x; 0..24) {
            foreach (y; x+1..24) {
                if (!(i & (1<<x))) continue;
                if (!(i & (1<<y))) continue;
                buf = min(buf, y-x);
                buf = min(buf, (x-y + 24) % 24);
            }
        }
        ans = max(ans, buf);
    }
    writeln(ans);
    return 0;
}
/* IMPORT /Users/yosupo/Program/dcomp/source/dcomp/scanner.d */
// module dcomp.scanner;

// import dcomp.array;

 
class Scanner {
    import std.stdio : File;
    import std.conv : to;
    import std.range : front, popFront, array, ElementType;
    import std.array : split;
    import std.traits : isSomeChar, isStaticArray, isArray; 
    import std.algorithm : map;
    File f;
    this(File f) {
        this.f = f;
    }
    char[512] lineBuf;
    char[] line;
    private bool succW() {
        import std.range.primitives : empty, front, popFront;
        import std.ascii : isWhite;
        while (!line.empty && line.front.isWhite) {
            line.popFront;
        }
        return !line.empty;
    }
    private bool succ() {
        import std.range.primitives : empty, front, popFront;
        import std.ascii : isWhite;
        while (true) {
            while (!line.empty && line.front.isWhite) {
                line.popFront;
            }
            if (!line.empty) break;
            line = lineBuf[];
            f.readln(line);
            if (!line.length) return false;
        }
        return true;
    }

    private bool readSingle(T)(ref T x) {
        import std.algorithm : findSplitBefore;
        import std.string : strip;
        import std.conv : parse;
        if (!succ()) return false;
        static if (isArray!T) {
            alias E = ElementType!T;
            static if (isSomeChar!E) {
                 
                 
                auto r = line.findSplitBefore(" ");
                x = r[0].strip.dup;
                line = r[1];
            } else static if (isStaticArray!T) {
                foreach (i; 0..T.length) {
                    bool f = succW();
                    assert(f);
                    x[i] = line.parse!E;
                }
            } else {
                FastAppender!(E[]) buf;
                while (succW()) {
                    buf ~= line.parse!E;
                }
                x = buf.data;
            }
        } else {
            x = line.parse!T;
        }
        return true;
    }
    int read(T, Args...)(ref T x, auto ref Args args) {
        if (!readSingle(x)) return 0;
        static if (args.length == 0) {
            return 1;
        } else {
            return 1 + read(args);
        }
    }
}


 
 

 
/* IMPORT /Users/yosupo/Program/dcomp/source/dcomp/array.d */
// module dcomp.array;

 
T[N] fixed(T, size_t N)(T[N] a) {return a;}

 
 

 
struct FastAppender(A, size_t MIN = 4) {
    import std.algorithm : max;
    import std.conv;
    import std.range.primitives : ElementEncodingType;
    import core.stdc.string : memcpy;

    private alias T = ElementEncodingType!A;
    private T* _data;
    private uint len, cap;
     
    @property size_t length() const {return len;}
    bool empty() const { return len == 0; }
     
    void reserve(size_t nlen) {
        import core.memory : GC;
        if (nlen <= cap) return;
        
        void* nx = GC.malloc(nlen * T.sizeof);

        cap = nlen.to!uint;
        if (len) memcpy(nx, _data, len * T.sizeof);
        _data = cast(T*)(nx);
    }
    void free() {
        import core.memory : GC;
        GC.free(_data);
    }
     
    void opOpAssign(string op : "~")(T item) {
        if (len == cap) {
            reserve(max(MIN, cap*2));
        }
        _data[len++] = item;
    }
     
    void insertBack(T item) {
        this ~= item;
    }
     
    void removeBack() {
        len--;
    }
     
    void clear() {
        len = 0;
    }
    ref inout(T) back() inout { assert(len); return _data[len-1]; }
    ref inout(T) opIndex(size_t i) inout { return _data[i]; }
     
    T[] data() {
        return (_data) ? _data[0..len] : null;
    }
}

 
 
/* IMPORT /Users/yosupo/Program/dcomp/source/dcomp/foundation.d */
// module dcomp.foundation;
 
static if (__VERSION__ <= 2070) {
    /*
    Copied by https://github.com/dlang/phobos/blob/master/std/algorithm/iteration.d
    Copyright: Andrei Alexandrescu 2008-.
    License: $(HTTP boost.org/LICENSE_1_0.txt, Boost License 1.0).
    */
    template fold(fun...) if (fun.length >= 1) {
        auto fold(R, S...)(R r, S seed) {
            import std.algorithm : reduce;
            static if (S.length < 2) {
                return reduce!fun(seed, r);
            } else {
                import std.typecons : tuple;
                return reduce!fun(tuple(seed), r);
            }
        }
    }
     
}

import core.bitop : popcnt;
static if (!__traits(compiles, popcnt(ulong.max))) {
    public import core.bitop : popcnt;
    int popcnt(ulong v) {
        return popcnt(cast(uint)(v)) + popcnt(cast(uint)(v>>32));
    }
}

bool poppar(ulong v) {
    v^=v>>1;
    v^=v>>2;
    v&=0x1111111111111111UL;
    v*=0x1111111111111111UL;
    return ((v>>60) & 1) != 0;
}

/*
This source code generated by dcomp and include dcomp's source code.
dcomp's Copyright: Copyright (c) 2016- Kohei Morita. (https://github.com/yosupo06/dcomp)
dcomp's License: MIT License(https://github.com/yosupo06/dcomp/blob/master/LICENSE.txt)
*/


Measured memory_bytes: 37156