//
// The problem is viewed more a scheduling problem. Rather than just have rounds
// we have positions in a round. That is, a round is a sequence. 
// Constraints are added such that the last contestants in a round
// cannot be in the first match of the next round
// NOTE: BAP4 is same as BAP3 (this) but uses value selectors (rando works well)
//
import static choco.Choco.*;
import choco.cp.model.CPModel;
import choco.kernel.model.Model;
import choco.kernel.model.variables.integer.IntegerVariable;
import choco.cp.solver.CPSolver;
import choco.kernel.solver.Solver;
import choco.kernel.solver.variables.integer.IntDomainVar;
import choco.cp.solver.search.integer.varselector.*;
import choco.cp.solver.search.integer.valselector.*;

public class BAP3 {

    Model model;
    Solver solver;
    int n;                        // contestants
    int m;                        // maximum number of matches in a round
    int matches;                  // number of matches
    IntegerVariable[] fMatch;     // flattened match
    int rounds;                   // number of rounds
    IntegerVariable[][] match;    // match[i][j] = k <-> contestants i and j are in a match in round k/m position k%m

    BAP3 (int n,int boats) {
	this.n     = n;
	this.m     = boats/2;
	matches    = n*(n-1)/2;
	rounds     = (int)Math.ceil((double)matches/(double)m);
	model      = new CPModel();
	solver     = new CPSolver();
	match      = new IntegerVariable[n][n];
	fMatch     = new IntegerVariable[matches];

	for (int i=0,k=0;i<n-1;i++)
	    for (int j=i+1;j<n;j++,k++)
		fMatch[k] = match[i][j] = match[j][i] = makeIntVar("match["+ i +"]["+ j +"]",0,m*rounds-1);

	for (int i=0;i<n;i++) match[i][i] = constant(m*rounds+i);
	//
	// leading diagonal filled with wild entries
	//

	//for (int i=0;i<n;i++) model.addConstraint(allDifferent(match[i]));
	//
	// redundant
	//

	for (int i=0;i<n;i++)
	    for (int j=0;j<n-1;j++) 
		for (int k=j+1;k<n;k++)
		    model.addConstraint(neq(div(match[i][j],m),div(match[i][k],m)));
	//
	// for a competitor i, all his matches must take place in different rounds
	// where a round is match[i][j]/m
	//

	for (int i=0;i<n;i++)
	    for (int j=0;j<n-1;j++) 
		for (int k=j+1;k<n;k++)
		    model.addConstraint(neq(abs(minus(match[i][j],match[i][k])),1));
	//
	// If competitor i is in the last slot in a round 
	// Then that competitor is not allowed to be in first slot of next round
	//

	model.addConstraint(allDifferent(fMatch));
	//
	// every match takes place in a different time slot
	//

	solver.read(model);
	solver.setValIntSelector(new MidVal());
	//solver.setValIntSelector(new RandomIntValSelector());
	//solver.setVarIntSelector(new RandomIntVarSelector(solver));
    }

    boolean solve(){return solver.solve();}

     void result(){
	 int[][][] schedule = new int[rounds][m][2];
	 for (int i=0;i<rounds;i++)
	     for (int j=0;j<m;j++) schedule[i][j][0] = -1;
	 for (int i=0;i<n-1;i++)
	     for (int j=i+1;j<n;j++){
		 int slot = solver.getVar(match[i][j]).getVal();
		 int round = slot/m;
		 int position = slot%m;
		 schedule[round][position][0] = i;
		 schedule[round][position][1] = j;
	     }
	 System.out.println(n +" skippers  "+ (m*2) +" boats  "+ matches +" matches  "+ rounds +" flights  "+ m +" boatPairs");
	 for (int round=0;round<rounds;round++){
	     System.out.print("flight: "+ round);
	     for (int position=0;position<m;position++)
		 if (schedule[round][position][0] != -1) System.out.print(" ("+ schedule[round][position][0] +","+ schedule[round][position][1] +")");
	     System.out.println();
	 }
	 /*
	 for (int i=0;i<n;i++){
	     System.out.print(i +": ");
	     for (int j=0;j<n;j++)
		 System.out.print(solver.getVar(match[i][j]).getVal() +" ");
	     System.out.println();
	 }
	 */
    }

    void stats(){
	System.out.println("nodes: "+ solver.getNodeCount() +"   cpu: "+ solver.getTimeCount());
    }
     
    public static void main(String args[]) {
	int n = Integer.parseInt(args[0]);
	int m = Integer.parseInt(args[1]);
	BAP3 bap = new BAP3(n,m);
	System.out.println(bap.solve());
	bap.stats();
	bap.result();
    }
}