#include <cstdio>
using namespace std;
int i, j, k, l, r, q, Max, ok, a[100001], n, Maxx;
int main ()
{
    freopen("pq.in", "r", stdin);
    freopen("pq.out", "w", stdout);
    scanf("%d%d", &n, &q);
    for (i=1; i<=n; i++)
        scanf("%d", &a[i]);
    for (k=1; k<=q; k++){
        scanf("%d%d", &l, &r);
        Max=-1;
        for (i=l; i<r; i++){
            Maxx=-1;
            for (j=i+1; j<=r; j++){
                if (a[i]==a[j]) {
                   Maxx=j-i;
                   break;
                }
            }
            if (Maxx>Max) Max=Maxx;
        }
        printf("%d\n", Max);
    }
    return 0;
}