1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
#include <stdio.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <stack>

using namespace std;

typedef vector<int> VI;
typedef long long LL;
typedef pair<int,int> para;

#define FOR(x, b, e) for(int x = b; x <= (e); ++x)
#define FORD(x, b, e) for(int x = b; x >= (e); --x)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define VAR(v, n) __typeof(n) v = (n)
#define ALL(c) (c).begin(), (c).end()
#define SIZE(x) ((int)(x).size())
#define FOREACH(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define PB push_back
#define ST first
#define ND second
#define MP make_pair

#define M 201750

int a[M];

int main() {
  int n, x, j;

  REP(i,M) a[i]=0;
  scanf("%d", &n);
  REP(i,n) {
    scanf("%d", &x);
    a[x]++;
  }

  REP(i,M) {
    x=a[i];
    for (j=i+1; x>>=1; j++)
      a[j]+=x&1;
  }

  for (x=M-1; x>=0; x--)
    if (a[x]==1) break;

  printf("%d", x);
  return 0;
}