#include <bits/stdc++.h>
using namespace std;
int L = 2e5;
vector<vector<int>> g(L);
vector<int> dp(L), d(L, 0), par(L, -1);
vector<bool> used(L);
int dist;
int ask1(int u) {
  cout << "d " << u + 1 << endl;
  int t;
  cin >> t;
  if (t == -1) {
    while (true) {
    }
  }
  return t;
}
int ask2(int u) {
  cout << "s " << u + 1 << endl;
  int t;
  cin >> t;
  --t;
  if (t == -1) {
    while (true) {
    }
  }
  return t;
}
void dfs(int u) {
  used[u] = true;
  for (auto v : g[u]) {
    if (!used[v]) {
      d[v] = d[u] + 1;
      par[v] = u;
      dfs(v);
      dp[u] += dp[v];
    }
  }
  if (d[u] == dist) dp[u]++;
}
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n - 1; i++) {
    int u, v;
    cin >> u >> v;
    --u;
    --v;
    g[u].push_back(v);
    g[v].push_back(u);
  }
  dist = ask1(0);
  dfs(0);
  int q = 0;
  if (dist == 0) {
    cout << "! 1" << endl;
    return 0;
  } else {
    while (d[q] != dist) {
      int r = q;
      while (d[r] != dist) {
        int t = -1;
        int ma = 0;
        for (auto v : g[r]) {
          if (d[v] > d[r]) {
            if (dp[v] > ma) {
              ma = dp[v];
              t = v;
            }
          }
        }
        r = t;
      }
      int newdist = ask1(r);
      if (newdist == 0) {
        cout << "! " << r + 1 << endl;
        return 0;
      } else {
        while (d[r] * 2 != 2 * dist - newdist) {
          r = par[r];
        }
        q = ask2(r);
      }
    }
    cout << "! " << q + 1 << endl;
    return 0;
  }
  cin >> n;
}
