#include <bits/stdc++.h>
using namespace std;
template <typename T, typename S>
ostream &operator<<(ostream &os, const pair<T, S> &p) {
  return os << "(" << p.first << ", " << p.second << ")";
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
  os << "[";
  for (int i = 0; i < (int)v.size(); i++) {
    if (i) os << ", ";
    os << v[i];
  }
  return os << "]";
}
void debug() { cerr << "\n"; }
template <typename T, typename... Args>
void debug(T x, Args... args) {
  cerr << x << "; ";
  debug(args...);
}
int depthX, depth[200000], sub[200000];
vector<int> path, adj[200000];
int query(char c, int u) {
  cout << c << " " << u + 1 << endl;
  int ret;
  cin >> ret;
  return ret;
}
int dfsSub(int u, int p) {
  sub[u] = 1;
  for (int v : adj[u])
    if (v != p) {
      depth[v] = depth[u] + 1;
      sub[u] += dfsSub(v, u);
    }
  return sub[u];
}
void dfsHld(int u, int p) {
  path.push_back(u);
  int nxt = -1;
  for (int v : adj[u])
    if (v != p && (nxt == -1 || sub[v] > sub[nxt])) nxt = v;
  if (nxt != -1) dfsHld(nxt, u);
}
int dfs(int u, int p) {
  path.clear();
  dfsHld(u, p);
  int depthY = (depthX + depth[path.back()] - query('d', path.back())) / 2,
      y = path[depthY - depth[u]];
  if (depthX == depthY) return y;
  return dfs(query('s', y) - 1, y);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n;
  cin >> n;
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    adj[u - 1].push_back(v - 1);
    adj[v - 1].push_back(u - 1);
  }
  depthX = query('d', 0);
  depth[0] = 0;
  dfsSub(0, -1);
  cout << "! " << dfs(0, -1) + 1 << endl;
  return 0;
}
