diff --git a/2019-python/output/__init__.py b/2019-python/output/__init__.py
index 3a034d6..7fa2647 100644
--- a/2019-python/output/__init__.py
+++ b/2019-python/output/__init__.py
@@ -54,7 +54,7 @@ def answer(part_index, fmt_string):
 
 def ints(s):
     """Extract all integers from a string"""
-    return [int(n) for n in re.findall(r"\d+", s)]
+    return [int(n) for n in re.findall(r"-?\d+", s)]
 
 
 def mhd(a, b):
diff --git a/2019-python/output/day_12.py b/2019-python/output/day_12.py
new file mode 100644
index 0000000..a743b53
--- /dev/null
+++ b/2019-python/output/day_12.py
@@ -0,0 +1,109 @@
+from itertools import combinations
+from math import lcm
+
+from output import answer, ints  # , matrix, D, DD, ADJ, ints, mhd, mdbg, vdbg
+
+n = 12
+title = "The N-Body Problem"
+
+
+@answer(1, "Answer is {}")
+def part_1(outputs):
+    return outputs[0]
+
+
+@answer(2, "Actually, answer is {}")
+def part_2(outputs):
+    return outputs[1]
+
+
+def solve(data):
+    M = [[ints(l), [0, 0, 0]] for l in data.splitlines()]
+
+    def G(m):
+        def U(x, y):
+            if x > y:
+                return -1
+            elif x < y:
+                return 1
+            return 0
+
+        for i, j in combinations(range(len(m)), r=2):
+            m1 = m[i]
+            m2 = m[j]
+            g1, v1 = m1
+            g2, v2 = m2
+            x1, y1, z1 = g1
+            x2, y2, z2 = g2
+            a1, b1, c1 = v1
+            a2, b2, c2 = v2
+            m[i] = [
+                g1,
+                [
+                    a1 + U(x1, x2),
+                    b1 + U(y1, y2),
+                    c1 + U(z1, z2),
+                ],
+            ]
+            m[j] = [
+                g2,
+                [
+                    a2 + U(x2, x1),
+                    b2 + U(y2, y1),
+                    c2 + U(z2, z1),
+                ],
+            ]
+
+        return m
+
+    def V(m):
+        nm = []
+        for gv in m:
+            g, v = gv
+            x1, y1, z1 = g
+            x2, y2, z2 = v
+            nm.append(
+                [
+                    [
+                        x1 + x2,
+                        y1 + y2,
+                        z1 + z2,
+                    ],
+                    v,
+                ]
+            )
+        return nm
+
+    P1 = M.copy()
+    for _ in range(1000):
+        P1 = V(G(P1))
+    p1 = sum(sum(map(abs, p)) * sum(map(abs, k)) for p, k in P1)
+    P2 = M.copy()
+    p2 = []
+    for i, igv in enumerate(zip(*[g for g, v in P2])):
+        igv = [(g, 0) for g in igv]
+        Q = P2.copy()
+        C = 0
+        while True:
+            Q = V(G(Q))
+            C += 1
+            sg = list(zip(*[g for g, v in Q]))[i]
+            sv = list(zip(*[v for g, v in Q]))[i]
+            if list(zip(sg, sv)) == igv:
+                p2.append(C)
+                break
+    p2 = lcm(*p2)
+    return p1, p2
+
+
+if __name__ == "__main__":
+    with open("./input/12.txt", "r") as f:
+        inp = f.read().strip()
+
+    inp = solve(inp)
+
+    a = part_1(inp)
+    b = part_2(inp)
+
+    assert a == 12466
+    assert b == 360689156787864