#include <cstdio>
#include <algorithm>
#include <cmath>

using namespace std;

int n, m, a[200000][18],c[100002],p,l[100002],r,q,z[100002],s[100002],nru,k=1;
bool e;

void eul()
{
	for(int i=1; i<n; i++)
	{
		for(int j=1; j<n; j++)
			if(c[j]==i)
			{
				z[i]=j+1;
				break;
			}

	}
	while (c[p]==1)
	{
		p++;
	}
	p--;
	r=1;
	s[1]=1;
	a[k][0]=1;
	while(nru<p)
	{
		r++;
		if (z[s[r-1]])
		{
			s[r]=z[s[r-1]];
			k++;
			a[k][0]=s[r];
			if (a[k][0]==1)
				nru++;
			if (c[z[s[r-1]]-1]==c[z[s[r-1]]])
				z[s[r-1]]++;
			else
				z[s[r-1]]=0;
		}
		else
		{
			k++;
			a[k][0]=s[r-2];
			if(a[k][0]==1)
				nru++;
			r-=2;
		}

	}
}

int main()
{
    freopen("lca.in","r",stdin);
    freopen("lca.out","w",stdout);
    scanf("%d %d\n",&n,&m);
    l[1]=0;
    for(int i=2; i<=2*n-1; i++)
		l[i]=l[i/2]+1;
	c[0]=1;
    for(int i=1; i<n; i++)
		scanf("%d",&c[i]);
	a[1][0]=1;
	eul();
	for(int i=1; i<=n; i++)
		for(int j=1; j<=k; j++)
			if(a[j][0]==i)
				z[i]=j;
	p=1;
	for(int i=1; i<=l[2*n-1];i++)
	{
		p*=2;
		for (int j=1; j<=2*n-p ;j++)
			a[j][i]=min(a[j][i-1],a[j+p/2][i-1]);
	}
	for (int i=1; i<=m; i++)
	{
		scanf("%d %d",&q,&r);
		r=z[r];
		q=z[q];
		if(r<q)
			swap(r,q);
		p=pow(2,l[r-q+1]);
		printf("%d\n",min(a[q][l[r-q+1]],a[r-p+1][l[r-q+1]]));
	}
    return 0;
}