diff --git a/week12/On Her Majesty's Secret Service.cpp b/week12/On Her Majesty's Secret Service.cpp
new file mode 100644
index 0000000..ad6d205
--- /dev/null
+++ b/week12/On Her Majesty's Secret Service.cpp	
@@ -0,0 +1,123 @@
+#include <bits/stdc++.h>
+// BGL includes
+#include <boost/graph/adjacency_list.hpp>
+#include <boost/graph/dijkstra_shortest_paths.hpp>
+#include <boost/graph/max_cardinality_matching.hpp>
+
+typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS,
+  boost::no_property, boost::property<boost::edge_weight_t, int> >      graph;
+  
+typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS,
+  boost::no_property> graph_undirected;
+typedef boost::graph_traits<graph_undirected>::vertex_descriptor vertex_desc_undirected;
+
+using namespace std;
+
+int n,m,a,s,c,d;
+vector<vector<int>> dist_map;
+vector<int> agents;
+vector<int> shelters;
+
+bool valid(int distance) {
+ 
+  graph_undirected G(a + s*c);
+  
+  int asize = agents.size();
+  int ssize = shelters.size();
+  
+  for(int i = 0; i < asize; i++) {
+    for(int j = 0; j < ssize; j++) {
+      
+      int aindex = agents[i];
+      int sindex = shelters[j];
+    
+      if(dist_map[aindex][sindex] == INT_MAX)
+        continue;
+      
+      if(dist_map[aindex][sindex] + d <= distance)
+        boost::add_edge(i,asize + j,G);
+      if(c == 2 && dist_map[aindex][sindex] + 2*d <= distance) 
+        boost::add_edge(i,asize+ssize+j,G);
+    }
+  }
+  
+  int size = boost::num_vertices(G);
+  std::vector<vertex_desc_undirected> mate_map(size); 
+ 
+  boost::edmonds_maximum_cardinality_matching(G,
+    boost::make_iterator_property_map(mate_map.begin(), boost::get(boost::vertex_index, G)));
+  
+  int matching_size = boost::matching_size(G,
+    boost::make_iterator_property_map(mate_map.begin(), boost::get(boost::vertex_index, G)));
+    
+  return matching_size == asize;
+}
+
+void solve() {
+  
+  cin >> n >> m >> a >> s >> c >> d;
+  
+  graph G(n);
+  
+  for(int i = 0; i < m;i++) {
+    char w;
+    int x,y,z;
+    cin >> w >> x >> y >> z;
+
+    if(w == 'S') {
+      boost::add_edge(x,y,z,G);
+    }
+    if(w == 'L') {
+      boost::add_edge(x,y,z,G);
+      boost::add_edge(y,x,z,G);
+    }
+  }
+  
+  agents = vector<int>(a);
+  shelters = vector<int>(s);
+  
+  for(int i = 0; i < a;i++)  {
+    cin >> agents[i];
+  }
+  for(int i = 0; i < s;i++) {
+    cin >> shelters[i];
+  } 
+
+  dist_map = vector<vector<int>>(n,vector<int>(n));
+  
+  for(int from = 0; from < n;from++) {
+    boost::dijkstra_shortest_paths(G, from ,boost::distance_map(boost::make_iterator_property_map(
+      dist_map[from].begin(), boost::get(boost::vertex_index, G))));
+  }
+
+  // Binary search on the solution space
+  int start = 0;
+  int end = INT_MAX / 2;
+  
+  while(start < end) {
+    int middle = (start + end) / 2;
+    if(valid(middle)) {
+      end = middle;
+    }
+    else {
+      start = middle+1;
+    }
+  }
+  
+  cout << start << endl;
+    
+  return;
+}
+
+signed main() {
+  
+  ios_base::sync_with_stdio(false);
+  cin.tie(0);
+  
+  int t;
+  cin >> t;
+  
+  while(t--) 
+    solve();
+  
+}
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