#include <bits/stdc++.h>
using namespace std;
vector<int> vec[200001], my, tmp;
int visited[200001], dist[200001];
void dd(int cur, int cnt, int p) {
  if (cnt == 0) {
    visited[cur]++;
    return;
  }
  for (int v : vec[cur]) {
    if (p != v) dd(v, cnt - 1, cur);
  }
}
int find(int cur, int &nn) {
  int ret = visited[cur] == 2;
  for (int v : vec[cur]) {
    if (dist[v] > dist[cur]) {
      ret += find(v, nn);
    }
  }
  if (ret * 2 >= (int)my.size()) {
    nn = cur;
    return -1000;
  }
  return ret;
}
void init(int cur, int cnt, int p) {
  dist[cur] = cnt;
  for (int v : vec[cur]) {
    if (p != v) init(v, cnt + 1, cur);
  }
}
int main() {
  int n, a, b, now = 1, next, nwd, nxd;
  scanf("%d", &n);
  for (int i = 1; i < n; i++) {
    scanf("%d %d", &a, &b);
    vec[a].push_back(b);
    vec[b].push_back(a);
    my.push_back(i);
  }
  init(1, 0, 1);
  my.push_back(n);
  bool flag = true;
  while (true) {
    if (flag) {
      printf("d %d\n", now);
      fflush(stdout);
      scanf("%d", &nwd);
      memset(visited, 0, sizeof(visited));
      dd(now, nwd, now);
      tmp.clear();
      for (int v : my) {
        if (visited[v]) {
          tmp.push_back(v);
          visited[v]++;
        }
      }
      my = tmp;
      flag = false;
    }
    if (my.size() == 1) {
      printf("! %d", my[0]);
      fflush(stdout);
      return 0;
    }
    find(now, next);
    if (now == next) {
      printf("s %d\n", now);
      fflush(stdout);
      scanf("%d", &now);
      flag = true;
      continue;
    }
    printf("d %d\n", next);
    fflush(stdout);
    scanf("%d", &nxd);
    if (dist[next] - dist[now] == nwd - nxd) {
      now = next;
      nwd = nxd;
    }
    memset(visited, 0, sizeof(visited));
    dd(next, nxd, next);
    tmp.clear();
    for (int v : my) {
      if (visited[v]) {
        tmp.push_back(v);
        visited[v]++;
      }
    }
    my = tmp;
  }
  return 0;
}
