#include <stdio.h>
#include <math.h>
#include <iostream>
using namespace std;

struct nod{

int inf;
nod *urm;
}*l[100005];
int a,b,k,rmq[100005][20];
int x,n,q,h[100005],use[100005];
void adaug(nod *&p,int x){
nod *u;
u=new nod;
u->inf=x;
u->urm=p;
p=u;
return;

}
int kk,st[1000005];
void df(int x,int height){
nod *p;
use[x]=1;
h[++kk]=height;
st[kk]=x;
for(p=l[x];p;p=p->urm)
    if(!use[p->inf]){ df(p->inf,height+1);

st[++kk]=x;
h[kk]=height;}

}
int j;
int main()
{   freopen("lca.in","r",stdin);
    freopen("lca.out","w",stdout);
    int i;

    scanf("%d%d",&n,&q);
    for(i=2;i<=n;i++) {
        scanf("%d",&x);
        adaug(l[x],i);
        adaug(l[i],x);

    }
    df(1,0);


n=kk;
    for(i=1;i<=n;i++) rmq[i][0]=i;
    for(j=1;(1<<j)<=n;j++)
    for(i=1;i<=n-(1<<j)+1;i++){
        if(h[rmq[i][j-1]]<h[rmq[i+(1<<(j-1))][j-1]]) rmq[i][j]=rmq[i][j-1];
        else rmq[i][j]=rmq[i+(1<<(j-1))][j-1];



    }
for(k=1;k<=q;k++){
    scanf("%d%d",&a,&b);
    int log=(int)(log2(b-a+1));
printf("%d\n",min(h[rmq[a][log]],h[rmq[b-(1<<log)+1][log]])+1);

}
    return 0;
}