#include <bits/stdc++.h>
#define inf 2333333333333333
#define N 1000010
#define p(a) putchar(a)
#define For(i,a,b) for(int i=a;i<=b;++i)
typedef unsigned char uchar;
//by war
//2020.9.15
using namespace std;
using namespace cv;
uchar b[10000010];
Mat image0,image1;
vector<Mat> v;
int pos;
void in(int &x){
    
 
int y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(int x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

uchar*  get_pixel(const uchar *img, int
 
 x, int y,int step){
        return (uchar*)(img+y*step+x*3);
}


void getChannel(const uchar *input, int width, int height, int inStep, int inChannels,  int channelToGet ){
    pos=0;
    For(i,0,height-1)
        For(j,0,width-1){
            auto k=get_pixel(input,j,i,inStep);
            b[pos++]=*(k+channelToGet);
        }
}


signed main(){
    image0
 
=imread("/Users/war/Downloads/dog.PNG");
    For(i,0,2){
        getChannel(image0.data, image0.cols, image0.rows, (int)image0.step, image0.channels(),i);
        Mat image (image0.cols, image0.rows, CV_8UC1, b, (int)image0.step/3);
        v.push_back(Mat::zeros(image0.cols, image0.rows, CV_8UC2));
        merge(v,image);
        v.pop_back();
        imshow("dog",image);
        waitKey(-1);
    }
    return 0;
}