#include <bits/stdc++.h>
using namespace std;

ifstream fin("lca.in");
ofstream fout("lca.out");

int e[250001];
int euler[250001];
int niv[250001];
int a[100005];
int rmq[20][250001];
vector<int> L[250001];
int n, m, Q;

void DFSE(int nr, int k)
{
    euler[++m] = k;
    niv[m] = nr;
    a[k] = m;
    for(auto w : L[k])
    {
        DFSE(nr + 1, w);
        euler[++m] = k;
        niv[m] = nr;
    }
}

void MakeE()
{
    int i;
    for(i=2;i<=m;i++)
        e[i] = e[i/2] + 1;
}

void RMQ()
{
    int i, j, l{};
    for(i=1;i<=m;i++)
        rmq[0][i] = i;
    for(i=1;i<=e[m];i++)
    {
        l = (1 << l);
        for(j=1;j<=m-l+1;j++)
            if(niv[rmq[i-1][j]] <= niv[rmq[i-1][j+l/2]]) rmq[i][j] = rmq[i-1][j];
            else rmq[i][j] = rmq[i-1][j + l/2];
    }
}

int main()
{
    ios_base::sync_with_stdio(0);
    fin.tie(0);
    fout.tie(0);
    int i, x, y;
    fin >> n >> Q;
    for(i=2; i<=n; i++)
    {
        fin >> x;
        L[x].push_back(i);
    }
    DFSE(1, 1);
    MakeE();
    RMQ();
    for(i=1; i<=Q; i++)
    {
        fin >> x >> y;
        x = a[x];
        y = a[y];
        if(x > y) swap(x, y);
        int expo = e[y - x + 1];
        int l = (1 << expo);
        if(niv[rmq[expo][x]] <= niv[rmq[expo][y-l+1]])
            fout << e[rmq[expo][x]] << "\n";
        else fout << e[rmq[expo][y-l+1]] << "\n";
    }
    fin.close();
    fout.close();
    return 0;
}