#include <bits/stdc++.h>
using namespace std;
int n, d;
vector<int> adj[200010];
int par[200010];
int dd[200010];
int sz[200010];
int vis[200010];
void dfs(int v, int p) {
  for (int e : adj[v]) {
    if (e != p) {
      par[e] = v;
      dd[e] = dd[v] + 1;
      dfs(e, v);
    }
  }
}
int dfs_sz(int v, int p) {
  sz[v] = 1;
  for (int e : adj[v]) {
    if (e != p && !vis[e]) {
      sz[v] += dfs_sz(e, v);
    }
  }
  return sz[v];
}
int dfs_root(int v, int p, int n) {
  for (int e : adj[v]) {
    if (e != p && !vis[e] && 2 * sz[e] > n) {
      return dfs_root(e, v, n);
    }
  }
  return v;
}
bool check(int v, int p, int val) {
  if (v == val) return true;
  for (int e : adj[v]) {
    if (e != p && !vis[e] && check(e, v, val)) return true;
  }
  return false;
}
void centroid(int v) {
  dfs_sz(v, v);
  int c = dfs_root(v, v, sz[v]);
  vis[c] = true;
  cout << "d " << c << endl;
  int dist;
  cin >> dist;
  if (dist == 0) {
    cout << "! " << c << endl;
  } else if (dist + dd[c] == d) {
    cout << "s " << c << endl;
    int nxt;
    cin >> nxt;
    for (int e : adj[c]) {
      if (!vis[e] && e != par[c]) {
        if (check(e, c, nxt)) {
          centroid(e);
        }
      }
    }
  } else {
    centroid(par[c]);
  }
}
int main() {
  cin.tie(0)->sync_with_stdio(0);
  cin >> n;
  for (int i = 0; i < n - 1; i++) {
    int a, b;
    cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }
  cout << "d 1" << endl;
  cin >> d;
  dfs(1, 0);
  centroid(1);
  return 0;
}
