1018.cpp

#include<iostream>
#include <string>
#include <algorithm>
#include <utility>
using namespace std;

string WB[8] = {
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW"
};
string BW[8] = {
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB",
    "BWBWBWBW",
    "WBWBWBWB"
};

string board[50];

int WB_cnt(int x, int y)
{
    int cnt =0;
    for(int i=0; i<8; i++){
        for(int j=0; j<8; j++){
            if(board[x+i][y+j] !=WB[i][j]){
                cnt ++;
            }
        }
    }
    return cnt;
}

int BW_cnt(int x, int y)
{
    int cnt =0;
    for(int i=0; i<8; i++){
        for(int j=0; j<8; j++){
            if(board[x+i][y+j] !=BW[i][j]){
                cnt ++;
            }
        }
    }
    return cnt;
}

int main()
{
ios::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);

    int size[2];
    int cnt;
    int min_val = 2501;
    pair<int,int> p1;
    cin >> p1.first >> p1.second;

    for (int i=0; i<p1.first; i++){
        cin >> board[i];
    }
    for(int i=0; i<=p1.first-8; i++){
        for(int j=0; j<=p1.second-8; j++){
            int tmp;
            tmp = min(WB_cnt(i,j),BW_cnt(i,j));
            if(tmp < min_val){
                min_val = tmp;
            }
        }
    }
    cout << min_val;

    return 0;
}