#include <cstdio>
        #include <vector>
        using namespace std;
        vector <int> g[100001];
        int tata[100001], euler[100001], nivel[100001], rmq[20][100001], lg[100001], m=1;
        int min (int x, int y)
        {
            if (x<y) return x;
            return y;
        }
        void RMQ (int n)
        {
            int i, j, x;
            for (i=1; (1<<i)<=n; i++)
            {
                x=1<<(i-1);
                for (j=1; j<=n-(1<<i)+1; j++)
                {
                    rmq[i][j]=min(rmq[i-1][j],rmq[i-1][j+x]);
                }
            }
            rmq[i][1]=min(rmq[i-1][1],rmq[i-1][2]);
        }
        void dfs (int x, int p)
        {
            int i;
            for (i=0; i<g[x].size(); i++)
            {
                euler[++m]=g[x][i];
                nivel[m]=p+1;
                dfs(g[x][i],p+1);
            }
        }
        int main()
        {
            int n, t, i, x, y, k;
            freopen("lca.in","r",stdin);
            freopen("lca.out","w",stdout);
            scanf("%d%d",&n,&t); lg[1]=0; euler[1]=1; nivel[1]=0;
            for (i=2; i<=n; i++)
            {
                scanf("%d",&tata[i]);
                g[tata[i]].push_back(i);
                lg[i]=lg[i/2]+1;
            }
            dfs(1,0);
            for (i=1; i<=m; i++) rmq[0][i]=nivel[i];
            RMQ(n);
            for (i=1; i<=t; i++)
            {
                scanf("%d",&x,&y);
                k=lg[y-x+1];
                printf("%d\n",min(rmq[k][x],rmq[k][y-(1<<k)+1]));
            }
            fclose(stdin);
            fclose(stdout);
            return 0;
        }