diff --git a/CMakeLists.txt b/CMakeLists.txt
index 24b0e79..d018e4b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -16,7 +16,7 @@ add_library(smmincov STATIC
 add_executable(
   espresso
   src/main.cpp
-        src/Cover.cpp src/Cover.hpp src/Cube.cpp src/Cube.hpp src/Pla.cpp src/Pla.hpp src/SMMincov.cpp)
+        src/Cover.cpp src/Cover.hpp src/Cube.cpp src/Cube.hpp src/Pla.cpp src/Pla.hpp src/SMMincov.cpp src/Cost.cpp src/Cost.hpp)
 target_link_libraries(espresso smmincov)
 
 set_property(TARGET espresso PROPERTY CXX_STANDARD 20)
diff --git a/src/Cost.cpp b/src/Cost.cpp
new file mode 100644
index 0000000..6e57ca5
--- /dev/null
+++ b/src/Cost.cpp
@@ -0,0 +1,5 @@
+//
+// Created by yqszxx on 10/4/21.
+//
+
+#include "Cost.hpp"
diff --git a/src/Cost.hpp b/src/Cost.hpp
new file mode 100644
index 0000000..71fa757
--- /dev/null
+++ b/src/Cost.hpp
@@ -0,0 +1,21 @@
+//
+// Created by yqszxx on 10/4/21.
+//
+
+#ifndef ESPRESSO_COST_HPP
+#define ESPRESSO_COST_HPP
+
+#include <cstddef>
+
+namespace espresso {
+
+class Cost {
+public:
+    size_t cubes;
+    size_t in;
+    size_t out;
+};
+
+} // namespace espresso
+
+#endif //ESPRESSO_COST_HPP
diff --git a/src/Cube.cpp b/src/Cube.cpp
index c28e3d3..e8e67da 100644
--- a/src/Cube.cpp
+++ b/src/Cube.cpp
@@ -283,3 +283,9 @@ size_t espresso::Cube::count() const {
 void espresso::Cube::reset() {
     data->reset();
 }
+
+espresso::Cube espresso::Cube::operator~() const {
+    Cube r;
+    (*r.data) = ~(*data);
+    return r;
+}
diff --git a/src/Cube.hpp b/src/Cube.hpp
index b364471..d00c064 100644
--- a/src/Cube.hpp
+++ b/src/Cube.hpp
@@ -30,6 +30,7 @@ class Cube {
     Cube operator + (const Cube& x) const;
     Cube& operator += (const Cube& x);
     Cube operator & (const Cube& x) const;
+    Cube operator ~ () const;
     bool operator <= (const Cube& x) const; // implies
     bool operator <=> (const Cube& x) const; // disjoint
     bool operator == (const Cube& x) const;
diff --git a/src/Pla.cpp b/src/Pla.cpp
index e6b7afa..ad4d258 100644
--- a/src/Pla.cpp
+++ b/src/Pla.cpp
@@ -404,3 +404,13 @@ void PLA::expand() {
         }
     }
 }
+
+Cost PLA::cost() const {
+    Cost cost{};
+    for (auto& c: F.cubes) {
+        cost.in += (~((*c) + Cube::getOutputMask())).count();
+        cost.out += ((*c) & Cube::getOutputMask()).count();
+        cost.cubes++;
+    }
+    return cost;
+}
diff --git a/src/Pla.hpp b/src/Pla.hpp
index a58d9b5..6b156c8 100644
--- a/src/Pla.hpp
+++ b/src/Pla.hpp
@@ -6,6 +6,7 @@
 #define ESPRESSO_PLA_HPP
 
 #include "Cover.hpp"
+#include "Cost.hpp"
 
 namespace espresso {
 
@@ -14,6 +15,7 @@ class PLA {
     explicit PLA();
     void dump() const;
     void expand();
+    Cost cost() const;
 
 private:
     Cover F, D, R;
diff --git a/src/main.cpp b/src/main.cpp
index 62f97a9..81e60d6 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -7,7 +7,11 @@
 
 int main(int, char*[]) {
     espresso::PLA pla;
+    espresso::Cost cost = pla.cost();
+    std::cerr << "I:c=" << cost.cubes << ",in=" << cost.in << ",out=" << cost.out << ",total=" << cost.in + cost.out << std::endl;
     pla.expand();
     pla.dump();
+    cost = pla.cost();
+    std::cerr << "O:c=" << cost.cubes << ",in=" << cost.in << ",out=" << cost.out << ",total=" << cost.in + cost.out << std::endl;
     return EXIT_SUCCESS;
 }