diff --git a/bit_difference.py b/bit_difference.py
old mode 100644
new mode 100755
diff --git a/charging_chaos.py b/charging_chaos.py
new file mode 100755
index 0000000..b248d54
--- /dev/null
+++ b/charging_chaos.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+
+# Inspired by descriptive part of oldest answer in
+# https://stackoverflow.com/questions/23308954
+
+def try_flips(Outlets, Devices, nDev, l):
+
+    # Try all the devices in all the outlets
+
+    # Find the flip configurations in bitwise form
+    # that are compatible (present) in all the outlets
+
+    S = set()
+    for j in range(len(Devices)):
+        S.add(Outlets[0] ^ Devices[j])
+
+    for i in range(1, len(Outlets)):
+        row = set()
+        for j in range(len(Devices)):
+            row.add(Outlets[i] ^ Devices[j])
+        S = S.intersection(row)
+
+    # If no common configuration is found, then no flip can
+    # solve this case
+
+    if len(S) == 0:
+        return "NOT POSSIBLE"
+
+    # Otherwise, pick the one with the smallest number of 1s
+    # (which represent flips) and return the number of flips
+
+    m = None
+    for s in S:
+        b = count_bits(s)
+        if m is None or b < m:
+            m = b
+    return str(m)
+
+
+def count_bits(x):
+    i = 0
+    while x != 0:
+        i = i + (x & 1)
+        x = x >> 1
+    return i
+
+
+def read_switches():
+    O = input().split()
+    for i in range(len(O)):
+        O[i] = int(O[i], 2)
+    return O
+
+
+if __name__ == "__main__":
+    t = int(input())
+
+    for i in range(t):
+        line = input().split()
+        n, l = int(line[0]), int(line[1])
+
+        Outlets = read_switches()
+        Devices = read_switches()
+
+        print("Case #" + str(i + 1) + ": " + try_flips(Outlets, Devices, n, l))
+
diff --git a/charging_chaos.txt b/charging_chaos.txt
new file mode 100644
index 0000000..e25f941
--- /dev/null
+++ b/charging_chaos.txt
@@ -0,0 +1,10 @@
+3
+3 2
+01 11 10
+11 00 10
+2 3
+101 111
+010 001
+2 2
+01 10
+10 01
diff --git a/modular_exponentiation.py b/modular_exponentiation.py
old mode 100644
new mode 100755