func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 2e5 + 5;   const int cipher = -1e9;   template <typename T>   void chkmax(T &x, T y) {     x = max(x, y);   }   template <typename T>   void chkmin(T &x, T y) {     x = min(x, y);   }   template <typename T>   void read(T &x) {     x = 0;     int f = 1;     char c = getchar();     for (; !isdigit(c); c = getchar())       if (c ==  - ) f = -f;     for (; isdigit(c); c = getchar()) x = x * 10 + c -  0 ;     x *= f;   }   template <typename T>   void write(T x) {     if (x < 0) x = -x, putchar( - );     if (x > 9) write(x / 10);     putchar(x % 10 +  0 );   }   template <typename T>   void writeln(T x) {     write(x);     puts(  );   }   struct SegmentTree {     struct Node {       int lc, rc;       int tag, Max, depth;     } a[MAXN * 2];     int root, size, n, depth[MAXN];     void update(int root) {       a[root].Max = max(a[a[root].lc].Max, a[a[root].rc].Max);       a[root].depth = max(a[a[root].lc].depth, a[a[root].rc].depth);     }     void build(int &root, int l, int r) {       root = ++size;       a[root].Max = -2e9;       a[root].tag = cipher;       if (l == r) {         a[root].depth = depth[l];         return;       }       int mid = (l + r) / 2;       build(a[root].lc, l, mid);       build(a[root].rc, mid + 1, r);       update(root);     }     void init(int x, int *y) {       n = x, size = 0;       for (int i = 1; i <= n; i++) depth[i] = 2 * y[i];       build(root, 1, n);     }     void pushdown(int root) {       if (a[root].tag != cipher && a[root].lc) {         a[a[root].lc].Max = a[root].tag + a[a[root].lc].depth;         a[a[root].lc].tag = a[root].tag;         a[a[root].rc].Max = a[root].tag + a[a[root].rc].depth;         a[a[root].rc].tag = a[root].tag;         a[root].tag = cipher;       }     }     void modify(int root, int l, int r, int ql, int qr, int x) {       if (l == ql && r == qr) {         a[root].Max = x + a[root].depth;         a[root].tag = x;         return;       }       pushdown(root);       int mid = (l + r) / 2;       if (mid >= ql) modify(a[root].lc, l, mid, ql, min(mid, qr), x);       if (mid + 1 <= qr) modify(a[root].rc, mid + 1, r, max(mid + 1, ql), qr, x);       update(root);     }     void modify(int l, int r, int x) { modify(root, 1, n, l, r, x); }     int query(int root, int l, int r, int ql, int qr, int x) {       pushdown(root);       int mid = (l + r) / 2;       if (l == ql && r == qr) {         if (l == r) {           if (a[root].Max > x)             return l;           else             return l - 1;         }         if (a[a[root].rc].Max > x)           return query(a[root].rc, mid + 1, r, mid + 1, r, x);         else           return query(a[root].lc, l, mid, l, mid, x);       }       if (mid >= qr) return query(a[root].lc, l, mid, ql, qr, x);       if (mid + 1 <= ql) return query(a[root].rc, mid + 1, r, ql, qr, x);       int tans = query(a[root].rc, mid + 1, r, mid + 1, qr, x);       if (tans == mid)         return query(a[root].lc, l, mid, ql, mid, x);       else         return tans;     }     int query(int l, int r, int x) { return query(root, 1, n, l, r, x); }   } ST;   vector<int> a[MAXN], points[MAXN];   int y[MAXN], t[MAXN], p[MAXN], ans[MAXN], val[MAXN];   int n, m, depth[MAXN], size[MAXN], son[MAXN];   int timer, father[MAXN], dfn[MAXN], up[MAXN];   void dfs(int pos, int fa) {     depth[pos] = depth[fa] + 1;     size[pos] = 1, son[pos] = 0;     for (auto x : a[pos])       if (x != fa) {         dfs(x, pos);         size[pos] += size[x];         if (size[x] > size[son[pos]]) son[pos] = x;       }   }   void efs(int pos, int fa, int from) {     up[pos] = from;     father[pos] = fa;     dfn[pos] = ++timer;     points[from].push_back(pos);     if (son[pos]) efs(son[pos], pos, from);     for (auto x : a[pos])       if (x != son[pos] && x != fa) efs(x, pos, x);   }   bool cmp(int a, int b) {     if (t[a] + depth[y[a]] == t[b] + depth[y[b]])       return y[a] < y[b];     else       return t[a] + depth[y[a]] < t[b] + depth[y[b]];   }   int main() {     read(n), read(m);     for (int i = 2; i <= n + 1; i++) {       int x;       read(x), x++;       a[x].push_back(i);     }     dfs(1, 0);     efs(1, 0, 1);     for (int i = 1; i <= m; i++) {       read(y[i]), y[i]++;       read(t[i]), p[i] = i;     }     sort(p + 1, p + m + 1, cmp);     static int tmp[MAXN];     for (int i = 1; i <= n + 1; i++) tmp[dfn[i]] = depth[i];     ST.init(n + 1, tmp);     ST.modify(1, 1, 2e9);     for (int i = 1; i <= m; i++) {       int pos = y[p[i]], x = pos, res = 0;       while (true) {         int f = up[x];         int tmp = ST.query(dfn[f], dfn[x], depth[pos] + t[p[i]]);         if (tmp == dfn[f] - 1)           res += dfn[x] - dfn[f] + 1;         else {           res += dfn[x] - tmp;           break;         }         x = father[f];       }       x = pos;       ans[p[i]] = t[p[i]] + 2 * res;       int tres = res;       while (tres) {         int f = up[x];         if (tres <= dfn[x] - dfn[f] + 1) {           ST.modify(dfn[x] - tres + 1, dfn[x], t[p[i]] + 2 * res - depth[pos]);           break;         } else {           tres -= dfn[x] - dfn[f] + 1;           ST.modify(dfn[f], dfn[x], t[p[i]] + 2 * res - depth[pos]);         }         x = father[f];       }     }     for (int i = 1; i <= m; i++) printf( %d  , ans[i]);     return 0;   }   