1 #include<bits/stdc++.h>
 2 using namespace std;
 3 typedef long long ll;
 4 const int inf=(int)(2e9);
 5 const ll INF=(ll)(5e18);
 6 const int N=1000010;//pay attention to the size of the array!!!
 7 const int M=30;
 8
 9 int n,l,r,num,ans;
10 int father[N][30],d[N];
11 vector<int> v[N];
12
13 void add_edge(int x,int y)
14 {
15     v[x].push_back(y);
16     father[y][0]=x;
17     for(int i=1;i<M;i++) father[y][i]=father[father[y][i-1]][i-1];
18     d[y]=d[x]+1;
19 }
20
21 void init()
22 {
23     num=5;
24     memset(father,0,sizeof(father));
25     for(int i=0;i<M;i++) father[1][i]=1;
26     d[1]=0; d[2]=d[3]=d[4]=1;
27 }
28
29 int LCA(int x,int y)
30 {
31     if(d[x]<d[y]) swap(x,y);
32     int dst=d[x]-d[y];
33     for(int i=M-1;i>=0;i--)
34     {
35         int tmp=(1<<i);
36         if(tmp<=dst)
37         {
38             dst-=tmp;
39             x=father[x][i];
40         }
41     }
42     for(int i=M-1;i>=0;i--)
43     {
44         if(father[x][i]==father[y][i]) continue;
45         x=father[x][i]; y=father[y][i];
46     }
47     return father[x][0];
48 }
49
50 int dis(int x,int y)
51 {
52     if(x==y) return 0;
53     int f=LCA(x,y);
54     return d[x]+d[y]-d[f]*2;
55 }
56
57 void solve(int x)
58 {
59     if(dis(x,l)>ans)
60     {
61         ans=dis(x,l);
62         r=x;//don't confuse the order of l&r
63     }
64     if(dis(x,r)>ans)
65     {
66         ans=dis(x,r);
67         l=x;
68     }
69 }
70
71 int main()
72 {
73     scanf("%d",&n);
74     init();
75     for(int i=2;i<=4;i++)
76     {
77         add_edge(1,i);
78     }
79     l=2,r=4,ans=2;
80     while(n--)
81     {
82         int x;
83         scanf("%d",&x);
84         add_edge(x,num);
85         add_edge(x,num+1);
86         solve(num);
87         num+=2;
88         printf("%d\n",ans);
89     }
90     return 0;
91 }