#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 7;
const int INF = 0x3f3f3f3f;
vector<int> G[maxn];
int askdis(int x) {
  cout << 'd' << " " << x << endl;
  int ret;
  cin >> ret;
  return ret;
}
int askson(int x) {
  cout << 's' << " " << x << endl;
  int ret;
  cin >> ret;
  return ret;
}
void answer(int x) { cout << "! " << x << endl; }
int sz[maxn], maxson[maxn], rt, treesz;
int dep[maxn], far[maxn];
bool vis[maxn];
void dfs(int u, int fa = -1) {
  far[u] = fa;
  for (auto& v : G[u])
    if (v != fa) {
      dep[v] = dep[u] + 1;
      dfs(v, u);
    }
}
void dfsrt(int u, int fa = -1) {
  sz[u] = 1;
  maxson[u] = 0;
  for (auto& v : G[u])
    if (v != fa && !vis[v]) {
      dfsrt(v, u);
      sz[u] += sz[v];
      maxson[u] = max(maxson[u], sz[v]);
    }
  maxson[u] = max(maxson[u], treesz - sz[u]);
  if (maxson[rt] > maxson[u]) rt = u;
}
int getsz(int u, int fa = -1) {
  int ret = 1;
  for (auto& v : G[u])
    if (fa != v && !vis[v]) {
      ret += getsz(v, u);
    }
  return ret;
}
int main() {
  int n;
  cin >> n;
  for (int i = 1, u, v; i < n; i++) {
    cin >> u >> v;
    G[u].push_back(v);
    G[v].push_back(u);
  }
  dep[1] = 0;
  dfs(1);
  treesz = n;
  int dis = askdis(1);
  int cur = 1;
  while (treesz != 1 && dis) {
    rt = 0;
    maxson[rt] = INF;
    dfsrt(cur);
    vis[rt] = 1;
    int dd = askdis(rt);
    if (!dd) {
      cur = rt;
      break;
    }
    if (dd + dep[rt] == dis) {
      cur = askson(rt);
      treesz = getsz(cur);
    } else {
      cur = far[rt];
      treesz = getsz(cur);
    };
  }
  answer(cur);
}
