#include <bits/stdc++.h>

using namespace std;
const int N = 1e5+5;
const int ssize=316;

int n, m;
int a[N];
int b[ssize+5][N];
int c[ssize+5][N];

int MAX(int x, int y){
    if (x>y) return x;
    return y;
}

struct NHO{
    int nho[N];
    long long tim[N];
    long long T=0;
    NHO(){
        memset(tim, 0, sizeof tim);
        T=1;
    }
    void reset(){T++;}
    int get(int x){
        if (tim[x]!=T) return 0;
        return nho[x];
    }
    void Set(int x, int val){
        tim[x] = T;
        nho[x] = val;
    }
};
NHO nho;

int main()
{
    if (fopen("test.inp","r")) freopen("test.inp","r",stdin);
    ios_base::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    cin >> n >> m;
    for(int i=1; i<=n; i++) cin >> a[i];
    vector<int> bb(a+1,a+1+n);
    sort(bb.begin(),bb.end());
    for(int i=1; i<=n; i++) a[i] = lower_bound(bb.begin(),bb.end(),a[i])-bb.begin();
    for(int k=0; (k+1)*ssize<=n; k++){
        nho.reset();
        int u = k*ssize + 1;
        for(int i=u; i<=n; i++){
            int j = nho.get(a[i]);
            if (j) b[k][i] = MAX(b[k][i-1],i-j);
            else nho.Set(a[i],i), b[k][i] = b[k][i-1];
        }
    }
    for(int k=0; k<=ssize; k++){
        nho.reset();
        int u = min(n,(k+1)*ssize);
        for(int i=u; i>=1; i--){
            int j = nho.get(a[i]);
            if (j) c[k][i] = MAX(c[k][i+1],j-i);
            else nho.Set(a[i],i), c[k][i] = c[k][i+1];
        }
    }
    while (m--){
        int l, r;
        cin >> l >> r;
        int u = (l-1)/ssize;
        int v = (r-1)/ssize;
        int res=0;
        if (v-u<=1){
            nho.reset();
            for(int i=l; i<=r; i++){
                int j = nho.get(a[i]);
                if (j) res = MAX(res,i-j);
                else nho.Set(a[i],i);
            }
            cout << res << '\n';
        }
        else{
            res = MAX(b[u+1][r],c[v-1][l]);
            nho.reset();
            for(int i=l; i<=(u+1)*ssize; i++){
                int j = nho.get(a[i]);
                if (j) res = MAX(res,i-j);
                else nho.Set(a[i],i);
            }
            for(int i=v*ssize+1; i<=r; i++){
                int j = nho.get(a[i]);
                if (j) res = MAX(res,i-j);
                else nho.Set(a[i],i);
            }
            cout << res << '\n';
        }
    }
    return 0;
}