#include <bits/stdc++.h>

 using namespace std;

 #define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);

 #define Rep(i,n) for (int i = 0; i < (n); ++i)

 #define For(i,s,t) for (int i = (s); i <= (t); ++i)

 #define rFor(i,t,s) for (int i = (t); i >= (s); --i)

 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)

 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)

 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)

 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)

 #define pr(x) cout << #x << " = " << x << "  "

 #define prln(x) cout << #x << " = " << x << endl

 #define LOWBIT(x) ((x)&(-x))

 #define ALL(x) x.begin(),x.end()

 #define INS(x) inserter(x,x.begin())

 #define ms0(a) memset(a,0,sizeof(a))

 #define msI(a) memset(a,inf,sizeof(a))

 #define msM(a) memset(a,-1,sizeof(a))

 #define MP make_pair

 #define PB push_back

 #define ft first

 #define sd second

 template<typename T1, typename T2>

 istream &operator>>(istream &in, pair<T1, T2> &p) {

     in >> p.first >> p.second;

     return in;

 }

 template<typename T>

 istream &operator>>(istream &in, vector<T> &v) {

     for (auto &x: v)

         in >> x;

     return in;

 }

 template<typename T1, typename T2>

 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {

     out << "[" << p.first << ", " << p.second << "]" << "\n";

     return out;

 }

 inline int gc(){

     static const int BUF = 1e7;

     static char buf[BUF], *bg = buf + BUF, *ed = bg;

     if(bg == ed) fread(bg = buf, , BUF, stdin);

     return *bg++;

 } 

 inline int ri(){

     int x = , f = , c = gc();

     for(; c<||c>; f = c=='-'?-:f, c=gc());

     for(; c>&&c<; x = x* + c - , c=gc());

     return x*f;

 }

 typedef long long LL;

 typedef unsigned long long uLL;

 typedef pair< double, double > PDD;

 typedef pair< int, int > PII;

 typedef pair< int, PII > PIPII;

 typedef pair< string, int > PSI;

 typedef pair< int, PSI > PIPSI;

 typedef set< int > SI;

 typedef vector< int > VI;

 typedef vector< VI > VVI;

 typedef vector< PII > VPII;

 typedef map< int, int > MII;

 typedef map< int, PII > MIPII;

 typedef map< string, int > MSI;

 typedef multimap< int, int > MMII;

 //typedef unordered_map< int, int > uMII;

 typedef pair< LL, LL > PLL;

 typedef vector< LL > VL;

 typedef vector< VL > VVL;

 typedef priority_queue< int > PQIMax;

 typedef priority_queue< int, VI, greater< int > > PQIMin;

 const double EPS = 1e-;

 const LL inf = 0x7fffffff;

 const LL infLL = 0x7fffffffffffffffLL;

 const LL mod = 1e9 + ;

 const int maxN = 1e4 + ;

 const LL ONE = ;

 const LL evenBits = 0xaaaaaaaaaaaaaaaa;

 const LL oddBits = 0x5555555555555555;

 struct Node{

     LL weight = , len;

     bool operator< (const Node &x) const {

         if(len == x.len) return weight > x.weight;

         return len < x.len;

     }

 };

 int N; 

 int main(){

     //freopen("MyOutput.txt","w",stdout);

     //freopen("input.txt","r",stdin);

     INIT();

     while(cin >> N) {

         priority_queue< Node > maxH;

         Rep(i, N) {

             Node t;

             cin >> t.len;

             maxH.push(t);

         }

         // nowLen: 记录当前处理第几层

         // nowMax: 记录 i + 1 层的最大值

         // tmpMax: 记录当前层 i 层的最大值

         LL nowLen = maxH.top().len, nowMax = , tmpMax = -;

         while(maxH.size() > ) {

             Node a = maxH.top(); maxH.pop();

             Node b = maxH.top(); maxH.pop();

             if(a.len == nowLen) {

                 // 代码看到这里也许会有疑问，就是如果 a.weight == 0 或是 b.weight == 0，难道不要把节点扔回去重新取吗？

                 // 其实不需要，因为它们就是最小的

                 // 设max(i)表示倒数第 i 层的频率最大值，min(i)表示倒数第 i 层的频率最小值

                 // 容易看出 max(i) <= 2^i, min(i) >= 2^{i-1}

                 // 于是倒数第 i + 1 层权值为 0 的节点会被赋值为 max(i)

                 // 而那些权值不为 0 的节点，权值必然大于等于2倍的min(i)，为 2^i，大于等于 max(i)

                 if(a.weight == ) a.weight = nowMax;

                 if(b.weight == ) b.weight = nowMax;

                 tmpMax = max(tmpMax, b.weight);

                 a.weight += b.weight;

                 --a.len;

                 maxH.push(a);

             }

             else {

                 nowLen = a.len;

                 nowMax = tmpMax;

                 tmpMax = -;

                 maxH.push(a);

                 maxH.push(b);

             }

         }

         cout << maxH.top().weight << endl;

     }

     return ;

 }