#include <bits/stdc++.h>
using namespace std;
int n;
vector<int> graf[2000010];
int gle[2000010];
int P[2000010];
int pod[2000010];
int odl_1;
void dfs(int v) {
  pod[v] = 1;
  for (auto x : graf[v]) {
    if (pod[x] == 0) {
      P[x] = v;
      gle[x] = gle[v] + 1;
      dfs(x);
      pod[v] += pod[x];
    }
  }
}
void centr(int v) {
  for (auto x : graf[v]) {
    if (pod[x] * 2 > pod[v]) {
      P[v] = x;
      P[x] = x;
      int cat = pod[v];
      pod[v] -= pod[x];
      pod[x] = cat;
      centr(x);
      return;
    }
  }
  cout << "d " << v << endl;
  cout.flush();
  int par;
  cin >> par;
  if (par == 0) {
    cout << "! " << v << endl;
    cout.flush();
    exit(0);
  }
  if (par + gle[v] == odl_1) {
    cout << "s " << v << endl;
    cout.flush();
    int x;
    cin >> x;
    if (x == -1) exit(0);
    P[x] = x;
    pod[v] = 0;
    centr(x);
  } else {
    int szuk;
    for (auto x : graf[v]) {
      if (gle[x] < gle[v]) szuk = x;
    }
    P[szuk] = szuk;
    pod[v] = 0;
    centr(szuk);
  }
}
int main() {
  cin >> n;
  for (int i = 0; i < (n - 1); ++i) {
    int t1, t2;
    cin >> t1 >> t2;
    graf[t1].push_back(t2);
    graf[t2].push_back(t1);
  }
  cout << "d 1" << endl;
  cout.flush();
  cin >> odl_1;
  if (odl_1 == 0) {
    cout << "! 1" << endl;
    cout.flush();
    return 0;
  }
  P[1] = 1;
  dfs(1);
  centr(1);
  return 0;
}
