#include <bits/stdc++.h>
using namespace std;
int main(){
  int X, Y, Z;
  cin >> Z >> Y >> X;
  bitset<2097152> SB,SW,TB,TW;
  for (int x = 0; x < X; x++) {
    for (int y = 0; y < Y; y++) {
      string S;
      cin >> S;
      for (int z = 0; z < Z; z++) {
        int t = z + 2 * Z * y + 4 * Y * Z * x;
        if (S[z] == 'B') {
          SB[t] = 1;
          SB[t + Z] = 1;
          SB[t + 2 * Y * Z] = 1;
          SB[t + 2 * Y * Z + Z] = 1;
          SB[t + 4 * X * Y * Z] = 1;
          SB[t + 4 * X * Y * Z + Z] = 1;
          SB[t + 4 * X * Y * Z + 2 * Y * Z] = 1;
          SB[t + 4 * X * Y * Z + 2 * Y * Z + Z] = 1;
        }
        if (S[z] == 'W') {
          SW[t] = 1;
          SW[t + Z] = 1;
          SW[t + 2 * Y * Z] = 1;
          SW[t + 2 * Y * Z + Z] = 1;
          SW[t + 4 * X * Y * Z] = 1;
          SW[t + 4 * X * Y * Z + Z] = 1;
          SW[t + 4 * X * Y * Z + 2 * Y * Z] = 1;
          SW[t + 4 * X * Y * Z + 2 * Y * Z + Z] = 1;
        }
      }
    }
  }
  for (int x = 0; x < X; x++) {
    for (int y = 0; y < Y; y++) {
      string T;
      cin >> T;
      for (int z = 0; z < Z; z++) {
        int t = z + 2 * Z * y + 4 * Y * Z * x;
        if (T[z] == 'B') TB[t] = 1;
        if (T[z] == 'W') TW[t] = 1;
      }
    }
  }
  int ans = X * Y * Z;
  for (int x = 0; x < X; x++) {
    for (int y = 0; y < Y; y++) {
      for (int z = 0; z < Z; z++) {
        int t = z + 2 * Z * y + 4 * Y * Z * x;
        ans = min(ans, int((SB & (TW << t)).count() + (SW & (TB << t)).count()));
      }
    }
  }
  cout << ans << endl;
  return 0;
}