diff --git a/__init__.py b/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/__main__.py b/__main__.py
new file mode 100644
index 0000000..16e4e82
--- /dev/null
+++ b/__main__.py
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+from .week2 import main
+
+main()
\ No newline at end of file
diff --git a/week2.py b/week2.py
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--- /dev/null
+++ b/week2.py
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+from .week1 import blood_cell_compatibility_lookup, BloodType
+import random
+
+
+class Dealer:
+    def __init__(self):
+        T = [[blood_cell_compatibility_lookup(r, d)
+              for d in BloodType ]
+             for r in BloodType]
+        self.M_B = [[random.randint(0, 1) for _ in range(8)] for _ in range(8)]
+
+        self.r = random.randint(0, 8)
+        self.s = random.randint(0, 8)
+
+        self.M_A = [[self.M_B[i][j] ^ T[i - self.r][j - self.s] for j in range(8)] for i in range(8)]
+
+    def rand_a(self):
+        return self.r, self.M_A
+
+    def rand_b(self):
+        return self.s, self.M_B
+
+
+class Alice:
+    def __init__(self, x, r, M_A):
+        self.x = x
+        self.r = r
+        self.M_A = M_A
+
+    def send(self):
+        # Should return u = x+r mod 2^n
+        self.u = (self.x + self.r) % 8
+        return self.u
+
+    def receive(self, v, z_b):
+        self.v = v
+        self.z_b = z_b
+
+    def output(self):
+        z = self.M_A[self.u][self.v] ^ self.z_b
+        return z
+
+
+class Bob:
+    def __init__(self, y, s, M_B):
+        self.y = y
+        self.s = s
+        self.M_B = M_B
+
+    def send(self):
+        # Should return v = y+s mod 2^n
+        v = (self.y + self.s) % 8
+        z_b = self.M_B[self.u][v]
+
+        return v, z_b
+
+    def receive(self, u):
+        self.u = u
+
+
+def ottt(recipient, donor):
+    dealer = Dealer()
+    alice = Alice(recipient, *dealer.rand_a())
+    bob = Bob(donor, *dealer.rand_b())
+    bob.receive(alice.send())
+    alice.receive(*bob.send())
+    z = alice.output()
+    return z
+
+
+def main():
+    green = 0
+    red = 0
+    for i, recipient in enumerate(BloodType):
+        for j, donor in enumerate(BloodType):
+            z = ottt(i, j)
+            lookup = blood_cell_compatibility_lookup(recipient, donor)
+            if lookup == z:
+                green += 1
+            else:
+                print(f"'{BloodType(donor).name} -> {BloodType(recipient).name}' should be {lookup}.")
+                red += 1
+    print("Green:", green)
+    print("Red  :", red)
+