func_code_string: #include <bits/stdc++.h>   using namespace std;   inline int gi() {     int x;     scanf( %d , &x);     return x;   }   struct Segment_Tree {     int dep, f, tag;   } t[200005 << 2];   struct Qry {     int x, tm, id;   } q[200005];   struct _Edge {     int to, next;   } Edge[200005 << 1];   int head[200005], CNT;   int top[200005], dfn[200005], rec[200005], dep[200005], son[200005], sz[200005],       ans[200005], fa[200005], n, m, tot;   inline void AddEdge(int u, int v) {     Edge[++CNT] = (_Edge){v, head[u]};     head[u] = CNT;     return;   }   void dfs1(int u, int deep) {     dep[u] = deep;     son[u] = 0;     sz[u] = 1;     for (int e = head[u]; e; e = Edge[e].next) {       int v = Edge[e].to;       dfs1(v, deep + 1);       sz[u] += sz[v];       if (!son[u] || sz[son[u]] < sz[v]) son[u] = v;     }     return;   }   void dfs2(int u, int upp) {     top[u] = upp;     dfn[u] = ++tot;     rec[tot] = u;     if (son[u])       dfs2(son[u], upp);     else       return;     for (int e = head[u]; e; e = Edge[e].next)       if (Edge[e].to != son[u]) dfs2(Edge[e].to, Edge[e].to);     return;   }   void Build(int o, int l, int r) {     t[o].f = t[o].tag = -2147483640;     if (l == r) {       t[o].dep = 2 * dep[rec[l]];       return;     }     int mid = (l + r) >> 1;     Build(o << 1, l, mid);     Build(o << 1 | 1, mid + 1, r);     t[o].dep = max(t[o << 1].dep, t[o << 1 | 1].dep);   }   inline void up(int o, int v) {     t[o].f = max(t[o].f, v + t[o].dep);     t[o].tag = max(t[o].tag, v);   }   inline void PushDown(int o) {     if (t[o].tag == -2147483640) return;     up(o << 1, t[o].tag);     up(o << 1 | 1, t[o].tag);     t[o].tag = -2147483640;     return;   }   void Update(int o, int l, int r, int ql, int qr, int v) {     if (ql <= l && r <= qr) {       up(o, v);       return;     }     int mid = (l + r) >> 1;     PushDown(o);     if (ql <= mid) Update(o << 1, l, mid, ql, qr, v);     if (mid < qr) Update(o << 1 | 1, mid + 1, r, ql, qr, v);     t[o].f = max(t[o << 1].f, t[o << 1 | 1].f);   }   int Query(int o, int l, int r, int ql, int qr) {     if (ql <= l && r <= qr) return t[o].f;     int mid = (l + r) >> 1, ret = -2147483640;     PushDown(o);     if (ql <= mid) ret = max(ret, Query(o << 1, l, mid, ql, qr));     if (mid < qr) ret = max(ret, Query(o << 1 | 1, mid + 1, r, ql, qr));     return ret;   }   inline int Calc(int x, int tm) {     int vl = dep[x] + tm, u = x, ret = 0, Ans;     while (u) {       if (Query(1, 1, n, dfn[top[u]], dfn[u]) <= vl) {         u = fa[top[u]];       } else {         int l = dfn[top[u]] + 1, r = dfn[u] + 1;         if (Query(1, 1, n, dfn[u], dfn[u]) > vl)           ret = u;         else {           while (l <= r) {             int mid = (l + r) >> 1;             if (Query(1, 1, n, mid, dfn[u]) <= vl)               ret = mid, r = mid - 1;             else               l = mid + 1;           }           ret = fa[rec[ret]];         }         break;       }     }     if (!ret) ret = 1;     u = x;     Ans = 2 * (dep[x] - dep[ret]) + tm;     while (top[u] ^ top[ret]) {       Update(1, 1, n, dfn[top[u]], dfn[u], Ans - dep[x]);       u = fa[top[u]];     }     Update(1, 1, n, dfn[ret], dfn[u], Ans - dep[x]);     return Ans;   }   inline bool cmp1(Qry A, Qry B) {     return ((dep[A.x] + A.tm) ^ (dep[B.x] + B.tm))                ? dep[A.x] + A.tm < dep[B.x] + B.tm                : A.x < B.x;   }   int main() {     n = gi() + 1;     m = gi();     for (int i = 2; i <= n; i++) fa[i] = gi() + 1, AddEdge(fa[i], i);     dfs1(1, 1);     dfs2(1, 1);     Build(1, 1, n);     for (int i = 1; i <= m; i++) q[i].x = gi() + 1, q[i].tm = gi(), q[i].id = i;     sort(q + 1, q + m + 1, cmp1);     for (int i = 1; i <= m; i++) ans[q[i].id] = Calc(q[i].x, q[i].tm);     for (int i = 1; i <= m; i++) printf( %d n , ans[i]);     return 0;   }   