#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;

const int MATRIX_LENGTH = 100;

int main()
{
    ofstream fout("result.txt");

    bool Matrix[MATRIX_LENGTH][MATRIX_LENGTH] = {{false}};
    int a, b, r;

    cout << "원의 중심: ";
    cin >> a >> b;

    cout << "반지름: ";
    cin >> r;

    for(int x = 0; x < MATRIX_LENGTH; x++) {
        /** (x - a)^2 + (y - b)^2 = r^2
            (y - b)^2 = r^2 - (x - a)^2
            (y - b)^2 = (r + x - a)(r - x + a)
            y - b = ±√{(r + x - a)(r - x + a)}
            ∴ y = b ± √{(r + x - a)(r - x + a)}
        **/
        int y1 = b + sqrt( (r + x - a) * (r - x + a) );
        int y2 = b - sqrt( (r + x - a) * (r - x + a) );

        if(0 <= y1 && y1 < MATRIX_LENGTH) {
            Matrix[y1][x] = true; Matrix[x][y1] = true;
        }
        if(0 <= y2 && y2 < MATRIX_LENGTH) {
            Matrix[y2][x] = true; Matrix[x][y2] = true;
        }
    }

    for(int i = 0; i < MATRIX_LENGTH; i++) {
        for(int j = 0; j < MATRIX_LENGTH; j++) {
            if(Matrix[i][j]) fout << "■";
            else fout << "□";
        }
        fout << endl;
    }

    return 0;
}