#include <bits/stdc++.h>
using namespace std;
const bool testing = false;
vector<int> e[100001];
set<int> f[100001];
vector<pair<int, int>> edges;
bool marked[100001];
int ic[100001];
int bucket[100001];
int bucketdepth[100001];
stack<int> roots;
int n, m;
int locate(int a) {
  vector<int> g;
  while (bucket[a] != a) {
    g.push_back(a);
    a = bucket[a];
  }
  for (int i : g) {
    bucket[i] = a;
    bucketdepth[i] = 0;
  }
  return a;
}
void join(int a, int b) {
  if (bucketdepth[a] < bucketdepth[b]) {
    bucket[a] = b;
    bucketdepth[a] = bucketdepth[b] + 1;
  } else {
    bucket[b] = a;
    bucketdepth[b] = bucketdepth[a] + 1;
  }
}
void removecircles() {
  memset(marked, 0, sizeof(marked));
  memset(bucketdepth, 0, sizeof(bucketdepth));
  for (int i = 1; i <= n; i++) {
    bucket[i] = i;
  }
  for (int i = 1; i <= n; i++) {
    if (!marked[i]) {
      stack<int> s;
      map<int, int> b;
      s.push(i);
      b[i] = b.size();
      marked[i] = true;
      while (s.size()) {
        int g = s.top();
        if (locate(g) != g) throw;
        while (f[g].size()) {
          int t = locate(*f[g].begin());
          if (t == g)
            f[g].erase(f[g].begin());
          else
            break;
        }
        if (!f[g].size()) {
          s.pop();
          b.erase(g);
          continue;
        } else {
          int t = locate(*f[g].begin());
          f[g].erase(f[g].begin());
          if (!marked[t]) {
            marked[t] = true;
            s.push(t);
            b[t] = b.size();
            continue;
          } else {
            if (b.find(t) != b.end()) {
              int circle = t;
              while (s.top() != circle) {
                auto x = b.find(s.top());
                if (x->second != b.size() - 1) throw;
                join(circle, x->first);
                for (int i : f[s.top()]) f[circle].insert(i);
                f[s.top()].clear();
                s.pop();
                b.erase(x);
              }
              int lc = locate(circle);
              bucket[circle] = circle;
              bucket[lc] = circle;
            }
          }
        }
      }
      if (b.size()) throw;
    }
  }
}
int getnext() {
  if (roots.size() == 0) return -1;
  int res = roots.top();
  roots.pop();
  return res;
}
void program() {
  cin >> n >> m;
  memset(ic, 0, sizeof(ic));
  for (int i = 0; i < m; i++) {
    int u, v;
    cin >> u >> v;
    edges.push_back(make_pair(u, v));
    f[u].insert(v);
  }
  removecircles();
  for (int i = 1; i <= n; i++) {
    f[i].clear();
    int j = locate(i);
    if (i == j) {
    } else {
      e[j].push_back(i);
    }
  }
  for (auto& i : edges) {
    int u = locate(i.first);
    int v = locate(i.second);
    if (u != v) f[u].insert(v);
  }
  for (int i = 1; i <= n; i++) {
    for (auto& g : f[i]) {
      ic[g]++;
    }
  }
  for (int i = 1; i <= n; i++) {
    int h = locate(i);
    if (!ic[i] && i == h) roots.push(i);
  }
  int prev = getnext();
  int preva = prev;
  if (e[prev].size()) {
    preva = e[prev][e[prev].size() - 1];
    e[prev].pop_back();
  }
  int next = getnext();
  int nexta = next;
  if (next != -1 && e[next].size()) {
    nexta = e[next][e[next].size() - 1];
    e[next].pop_back();
  }
  while (nexta != -1) {
    cout << "? " << preva << " " << nexta << endl;
    cout.flush();
    int t;
    cin >> t;
    if (t == -1) exit(-1);
    if (t == 1) {
      if (nexta != next)
        roots.push(next);
      else {
        for (auto& g : f[next]) {
          ic[g]--;
          if (!ic[g]) roots.push(g);
        }
      }
    } else {
      if (preva != prev)
        roots.push(prev);
      else {
        for (auto& g : f[prev]) {
          ic[g]--;
          if (!ic[g]) roots.push(g);
        }
      }
      preva = nexta;
      prev = next;
    }
    next = getnext();
    nexta = next;
    if (next != -1 && e[next].size()) {
      nexta = e[next][e[next].size() - 1];
      e[next].pop_back();
    }
  }
  cout << "! " << preva << endl;
  cout.flush();
}
int main() {
  if (!testing) {
    program();
    return 0;
  }
  FILE* fin = NULL;
  fin = fopen("in.txt", "w+");
  fprintf(fin, "\n4 2\n1 2\n3 4\n0\n1\n1");
  fclose(fin);
  freopen("in.txt", "r", stdin);
  printf("test case(1) => expected : \n");
  printf("? 1 3? 4 2? 3 2! 3");
  printf("test case(1) => found    : \n");
  program();
  return 0;
}
