129B

.gitignore

@@ -5,5 +5,4 @@ lib/
 pyvenv.cfg
 **/*.out
 Codeforces/C/225.cc
-UVa/10461.cc
 **/*.txt

Codeforces/B/129.cc

@@ -0,0 +1,41 @@
+#include <map>
+#include <unordered_set>
+#include <iostream>
+#include <iterator>
+
+using namespace std;
+
+int main() {
+    int n, m, a, b;
+    cin >> n >> m;
+    map<int, unordered_set<int>> adj;
+    for(int i = 0; i < m; ++i) {
+        cin >> a >> b;
+        adj[a].insert(b);
+        adj[b].insert(a);
+    }
+    unordered_set<int> to_kick, remaining;
+    for(int student = 1; student <= n; ++student) {
+        remaining.insert(student);
+    }
+    int answer{0};
+    while(true) {
+        for(auto student : remaining) {
+            if(adj[student].size() == 1)
+                to_kick.insert(student);
+        }
+        if(!to_kick.empty()) {
+            ++answer;
+            for(auto student_to_kick : to_kick) {
+                remaining.erase(student_to_kick);
+                for(auto other_student : adj[student_to_kick])
+                    adj[other_student].erase(student_to_kick);
+            }
+        }
+        else{
+            break;
+        }
+        to_kick = {};
+    }
+    cout << answer << endl;
+}