CSP suguru

package org.chocosolver.samples;
import org.chocosolver.solver.Model;
import org.chocosolver.solver.Solution;
import org.chocosolver.solver.variables.IntVar;

public class NQueen {

    public void modelAndSolve(){
        int n = 6, roll = 29;
        int group[][] = {
            {0, 0, 3, 5, 5, 5},
            {0, 3, 3, 3, 5, 6},
            {0, 2, 3, 4, 5, 6},
            {0, 2, 4, 4, 4, 6},
            {1, 2, 2, 4, 7, 6},
            {1, 1, 1, 1, 7, 6}
        };
        int board[][] = {
            {0, 0, 0, 0, 0, 0},
            {0, 0, 0, 5, 0, 3},
            {5, 0, 0, 0, 0, 0},
            {0, 1, 0, 0, 0, 0},
            {5, 0, 0, 0, 0, 5},
            {0, 0, 0, 0, 0, 0}
        };
        int numGroup[] = {0, 0, 0, 0, 0, 0, 0, 0};

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                numGroup[group[i][j]]++;
            }
        }

        Model model = new Model("book-6 problem-14 suguru");
        IntVar[][] vars = new IntVar[n][n];

        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (board[i][j] != 0) {
                    vars[i][j] = model.intVar("cell_" + i + "_" + j, board[i][j], board[i][j]);
                }
                else {
                    vars[i][j] = model.intVar("cell_" + i + "_" + j, 1, numGroup[group[i][j]]);
                }
            }
        }

        for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            for (int k = 0; k < n; k++) {
            for (int l = 0; l < n; l++) {
                if (i == k && j == l) {
                    continue;
                }

                if ((Math.abs(i - k) < 2 && Math.abs(j - l) < 2) || group[i][j] == group[k][l]) {
                    model.arithm(vars[i][j], "!=",vars[k][l]).post();
                }
            }
            }
        }}

        Solution solution = model.getSolver().findSolution();
        if(solution != null){
            System.out.println(solution.toString());
        }
    }

    public static void main(String[] args) {
        new NQueen().modelAndSolve();
    }

}