1 #include<bits/stdc++.h>
2 #define fi first
3 #define se second
4 #define pb(i) push_back(i)
5 #define rep(i,a,b) for(int i=a;i<=b;i++)
6 #define per(i,a,b) for(int i=b;i>=a;i--)
7 #define mem(a,b) memset(a,b,sizeof(a))
8 #define VI vector<int>
9 #define VLL vector<ll>
10 #define MPII map<pair<int,int>,int>
11 #define mp make_pair
12 #define PQI priority_queue<int>
13 using namespace std;
14 typedef long long ll;
15 typedef unsigned long long ull;
16 const int N = 1e6+10;
17 const int INF = 0x3f3f3f3f;
18 const int inf = - INF;
19 const int mod = 1e9+7;
20 const double pi = acos(-1.0);
21 const double eps=1e-5;
22 int n,pos=0;
23 int value[N],cnt[N];
24 int num[N];
25 int lft[N],rit[N];
26 int d[N][30];
27 void RMQ_init(){
28 memset(d,0,sizeof(d));
29 for(int i=0;i<=pos;i++) d[i][0]=cnt[i];
30 for(int j=1;(1<<j)<=pos;j++){
31 for(int i=1;i+(1<<j)-1<=pos;i++)
32 d[i][j]=max(d[i][j-1],d[i+(1<<(j-1))][j-1]);
33 }
34 }
35 int RMQ(int l,int r){
36 int ans=0;
37 if(num[l]==num[r]) return r-l+1;
38 ans=max(ans,max(rit[l]-l+1,r-lft[r]+1));
39 int k=0;
40 int L=rit[l]+1,R=lft[r]-1;
41 if(num[L]>num[R]) return ans;//中间没有其他数字
42 if(num[L]==num[R]) return max(ans,R-L+1);
43 while(1<<(k+1)<=num[R]-num[L]+1) k++;
44 return max(ans,max(d[num[L]][k],d[num[R]-(1<<k)+1][k]));
45 }
46 //vector<int>a;
47 int a[N];
48 int main(){
49 int q;
50 while(scanf("%d",&n)==1&&n){
51 scanf("%d",&q);
52 pos=0;
53 memset(num,0,sizeof(num));
54 memset(value,0,sizeof(value));
55 memset(lft,0,sizeof(lft));
56 memset(rit,0,sizeof(rit));
57 memset(cnt,0,sizeof(cnt));
58 a[0]=inf;
59 for(int i=1;i<=n;i++){
60 scanf("%d",&a[i]);
61 if(a[i]!=a[i-1]){
62 value[++pos]=a[i];
63 cnt[pos]++;
64 lft[i]=i;
65 }
66 else{
67 cnt[pos]++;
68 lft[i]=lft[i-1];
69 }
70 num[i]=pos;
71 }
72 for(int i=1;i<=n;i++)
73 rit[i]=lft[i]+cnt[num[i]]-1;
74 RMQ_init();
75 while(q--){
76 int l,r;
77 scanf("%d%d",&l,&r);
78 printf("%d
",RMQ(l,r));
79 }
80 }
81 system("pause");
82 return 0;
83 }
