diff --git a/build/CMakeFiles/HLlib.dir/src/HiddenLines.cpp.o b/build/CMakeFiles/HLlib.dir/src/HiddenLines.cpp.o
index 7b598d5..7017456 100644
Binary files a/build/CMakeFiles/HLlib.dir/src/HiddenLines.cpp.o and b/build/CMakeFiles/HLlib.dir/src/HiddenLines.cpp.o differ
diff --git a/build/CMakeFiles/main.dir/src/main.cpp.o b/build/CMakeFiles/main.dir/src/main.cpp.o
index 33bc6bf..56c18ed 100644
Binary files a/build/CMakeFiles/main.dir/src/main.cpp.o and b/build/CMakeFiles/main.dir/src/main.cpp.o differ
diff --git a/build/libHLlib.a b/build/libHLlib.a
index 160f57f..6ae4fa4 100644
Binary files a/build/libHLlib.a and b/build/libHLlib.a differ
diff --git a/build/main b/build/main
index e22dc28..0fc03d5 100755
Binary files a/build/main and b/build/main differ
diff --git a/src/HiddenLines.cpp b/src/HiddenLines.cpp
index af88472..8f6f6d5 100644
--- a/src/HiddenLines.cpp
+++ b/src/HiddenLines.cpp
@@ -152,11 +152,11 @@ std::set<Line> merge(std::set<Line> lh, std::set<Line> rh){
 	}
 }
 
-std::set<Line> HL::get_lines(){
+std::set<Line> HL::get_lines() const{
 	return lines;
 }
 
-std::set<Line> HL::get_sol(){
+std::set<Line> HL::get_sol() const{
 	std::set<Line> dummy;
 	return dummy;
 	//return sol;
diff --git a/src/HiddenLines.h b/src/HiddenLines.h
index e67bc7d..a681777 100644
--- a/src/HiddenLines.h
+++ b/src/HiddenLines.h
@@ -13,11 +13,11 @@ class HL
 		std::set<Line> gen_sol(std::set<Line>& ls);
 		std::set<Line> construct_HWprob();
 		
-		std::set<Line> get_lines();
-		std::set<Line> get_sol();
+		std::set<Line> get_lines() const;
+		std::set<Line> get_sol() const;
 
 	private:
-		//Solution is in form Line ID <vis_start, vis_end>
+		//Solution is in form (Line ID, (vis_start, vis_end))
 		std::set<std::pair<int, std::pair<double, double>>> sol;
 		std::set<Line> lines;
 };