#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 5;
vector<int> t[N];
int sz[N], p[N], n;
void init(int u = 1) {
  sz[u] = 1;
  int bestv = -1;
  for (int v : t[u]) {
    if (v == p[u]) continue;
    p[v] = u;
    init(v);
    sz[u] += sz[v];
  }
}
int query(char t, int node) {
  cout << t << ' ' << node << endl;
  int x;
  cin >> x;
  assert(x != -1);
  return x;
}
int find_cent(int u, int tar, int &d) {
  int best = -1, nxt;
  for (int v : t[u]) {
    if (v == p[u]) continue;
    if (sz[v] > best) {
      best = sz[v];
      nxt = v;
    }
  }
  if (best * 2 >= tar) {
    ++d;
    return find_cent(nxt, tar, d);
  } else {
    return u;
  }
}
void rem(int u, int t, int amt) {
  while (1) {
    sz[u] -= amt;
    if (u == t) break;
    u = p[u];
  }
}
int solve(int u, int d1) {
  if (d1 == 0) return u;
  int s1 = query('s', u);
  if (d1 == 1) return s1;
  --d1;
  u = s1;
  while (1) {
    int x = 0;
    int cent = find_cent(u, sz[u], x);
    int d2 = query('d', cent);
    if (d1 - d2 < x) {
      rem(cent, u, sz[cent]);
    } else {
      return solve(cent, d2);
    }
  }
}
int main() {
  cin.tie(0);
  cout.tie(0);
  ios_base::sync_with_stdio(0);
  cin >> n;
  for (int i = 0; i < n - 1; ++i) {
    int x, y;
    cin >> x >> y;
    t[x].push_back(y);
    t[y].push_back(x);
  }
  init();
  int ans = solve(1, query('d', 1));
  cout << "! " << ans << endl;
}
