Jzzhu has a big rectangular chocolate bar that consists of n × m unit squares. He wants to cut this bar exactly k times. Each cut must meet the following requirements:

  * each cut should be straight (horizontal or vertical); 
  * each cut should go along edges of unit squares (it is prohibited to divide any unit chocolate square with cut); 
  * each cut should go inside the whole chocolate bar, and all cuts must be distinct. 



The picture below shows a possible way to cut a 5 × 6 chocolate for 5 times.

<image>

Imagine Jzzhu have made k cuts and the big chocolate is splitted into several pieces. Consider the smallest (by area) piece of the chocolate, Jzzhu wants this piece to be as large as possible. What is the maximum possible area of smallest piece he can get with exactly k cuts? The area of a chocolate piece is the number of unit squares in it.

Input

A single line contains three integers n, m, k (1 ≤ n, m ≤ 109; 1 ≤ k ≤ 2·109).

Output

Output a single integer representing the answer. If it is impossible to cut the big chocolate k times, print -1.

Examples

Input

3 4 1


Output

6


Input

6 4 2


Output

8


Input

2 3 4


Output

-1

Note

In the first sample, Jzzhu can cut the chocolate following the picture below:

<image>

In the second sample the optimal division looks like this:

<image>

In the third sample, it's impossible to cut a 2 × 3 chocolate 4 times.
import java.util.* ;
import java.io.* ;
import java.util.regex.* ;
import java.text.* ;
import java.math.* ;

public class Main {
	public static void main( String[] args ) {
		InputStream isObj ;
		OutputStream osObj ;
		InputReader irObj ;
		PrintWriter pwObj ;
		String inputFileName , outputFileName ;
		File fObj1 , fObj2 ;
		int T , ind ;
		boolean hasMoreInput , hasTestCases ;
		ProblemSolver psObj ;
		//only variable to be changed here is hasTestCases and osObj(optional for file output)
		hasTestCases = ProblemSolver.HAS_TEST_CASES ;
		isObj = System.in ;
		osObj = System.out ;
		inputFileName = ProblemSolver.INPUT_FILE_NAME ;
		outputFileName = ProblemSolver.OUTPUT_FILE_NAME ;
		try {
			fObj1 = new File( System.getProperty( "user.dir" ).toString() + "\\" + inputFileName ) ;
			fObj2 = new File( System.getProperty( "user.dir" ).toString() + "\\" + outputFileName ) ;
			if( fObj1.exists() == false ) {
				fObj1 = new File( System.getProperty( "user.dir" ).toString() + "\\src\\" + inputFileName ) ;
				fObj2 = new File( System.getProperty( "user.dir" ).toString() + "\\src\\" + outputFileName ) ;
			}
			isObj = new FileInputStream( fObj1 ) ;
			if( ProblemSolver.DO_OUTPUT_TO_FILE == true ) {
				osObj = new FileOutputStream( fObj2 ) ;
			}
		}
		catch( Exception ex ) {
			ex.printStackTrace() ;
			isObj = System.in ;
			osObj = System.out ;
		}
		irObj = new InputReader( isObj ) ;
		pwObj = new PrintWriter( osObj ) ;
		try {
			psObj = new ProblemSolver() ;
			if( hasTestCases == true ) {
				//for input with test cases
				T = irObj.nextInt() ;
				for( ind = 1 ; ind <= T ; ind++ ) {        	
					psObj.clearPerCase() ;
					psObj.getInput( irObj ) ;
					psObj.solveCase( pwObj ) ;
				}
			}
			else {
				//for end of file input
				for( ind = 1 ; ; ind++ ) {        	
					psObj.clearPerCase() ;
					hasMoreInput = psObj.getInput( irObj ) ;
					if( hasMoreInput == false ) {
						break ;
					}
					psObj.solveCase( pwObj ) ;
				}
			}
			pwObj.flush() ;
			isObj.close() ;
			osObj.close() ;
		}
		catch( Exception ex ) {
			ex.printStackTrace() ;
			throw new RuntimeException( ex ) ;
		}
		finally {
			pwObj.close() ;
		}
	}
}

class ProblemSolver {
	public static final boolean HAS_TEST_CASES = false ;
	public static final String INPUT_FILE_NAME = "test.in" ;
	public static final String OUTPUT_FILE_NAME = "out.txt" ;
	public static final boolean DO_OUTPUT_TO_FILE = false ;
	
	public void solveCase( PrintWriter pwObj ) {
		long i , j , a , b , c , lo , hi , mi , d , e , f , mil , mir , x , y ;
		long res ;
		x = y = -1 ;
		res = Long.MIN_VALUE ;
		if( this.k > this.n + this.m - 2 ) {
			res = -1 ;
		}
		else {
			if( this.n > this.m ) {
				a = this.n ; 
				this.n = this.m ;
				this.m = a ;
			}
			if( this.k < this.n - 1 ) {
				i = this.k ;
				j = 0 ;
				b = this.n / ( i + 1 ) ;
				c = this.m / ( j + 1 ) ;
				e = b * c ;
				res = Math.max( res , e ) ;
			}
			if( this.k < this.m - 1 ) {
				i = 0 ;
				j = this.k ;
				b = this.n / ( i + 1 ) ;
				c = this.m / ( j + 1 ) ;
				e = b * c ;
				res = Math.max( res , e ) ;
			}
			a = this.n - 1 ;
			b = this.m - 1 ;
			if( this.k < this.n - 1 ) {
				lo = 0 ;
			}
			else {
				lo = this.k - ( this.n - 1 ) ;			
			}
			hi = Math.min( this.k , b ) ;
			while( lo <= hi ) {
				if( hi - lo < 100 ) {
					break ;
				}
				mil = ( 2 * lo + hi ) / 3 ;
				mir = ( lo + 2 * hi ) / 3 ;
				j = mil ;
				i = this.k - j ;
				b = this.n / ( i + 1 ) ;
				c = this.m / ( j + 1 ) ;
				e = b * c ;
				
				j = mil ;
				i = this.k - j ;
				b = this.n / ( i + 1 ) ;
				c = this.m / ( j + 1 ) ;
				f = b * c ;
				if( e <= f ) {
					lo = mil ;
				}
				else {
					hi = mir ;
				}				
				res = Math.max( res , e ) ;
				res = Math.max( res , f ) ;
			}
			for( j = lo ; j <= hi ; j++ ) {
				i = this.k - j ;
				b = this.n / ( i + 1 ) ;
				c = this.m / ( j + 1 ) ;
				a = b * c ;				
				res = Math.max( res , a ) ;
			}
		}
		pwObj.println( res ) ;
	}
	
	private void init() {
		//default values
		this.lim1 = 100010 ;
		this.lim2 = 110 ;
		this.cc = 1 ;
		this.ind = 0 ;
		this.declareArrays() ;
		this.fillAllArrays() ;
	}
	
	public boolean getInput( InputReader irObj ) {
		int i ;
		try {
			this.n = irObj.nextInt() ;
		}
		catch( Exception ex ) {
			return false ;
		}
		this.m = irObj.nextInt() ;
		this.k = irObj.nextInt() ;
		return true ;
	}
	
	private int lim1 , lim2 , cn , ind , cc ;
	private long n , m , k ;
	private String[] srr ;
	private Integer[] arr , brr ;
	private Node[] nrr ;
	private Long[] lrr ;
	private Integer[][] memo , done ;
	private ArrayList< Integer >[] adj_list ;
	
	public void clearPerCase() {
		this.incrementInd() ;
		this.incrementCc() ;
		this.n = 0 ;
		this.cn = 0 ;
	}
	
	private void declareArrays() {
		//array declarations
		this.arr = new Integer[ this.lim1 ] ;
		this.brr = new Integer[ this.lim1 ] ;
		this.lrr = new Long[ this.lim1 ] ;
		this.srr = new String[ this.lim1 ] ;
		this.nrr = new Node[ this.lim1 ] ;
		this.memo = new Integer[ this.lim2 ][ this.lim2 ] ;
		this.done = new Integer[ this.lim2 ][ this.lim2 ] ;
		this.adj_list = new ArrayList[ this.lim1 ] ;
	}
	
	private void fillAllArrays() {
		int i ;
		//array initiations
		Arrays.fill( this.arr , 0 ) ;
		Arrays.fill( this.brr , 0 ) ;
		Arrays.fill( this.lrr , ( long ) 0 ) ;
		for( Integer zrr[] : this.memo ) {
			Arrays.fill( zrr , -1 ) ;
		}
		for( Integer zrr[] : this.done ) {
			Arrays.fill( zrr , 0 ) ;
		}
		for( i = 0 ; i < this.lim1 ; i++ ) {
			this.srr[ i ] = new String( "" ) ;
			this.nrr[ i ] = new Node( Integer.MIN_VALUE , Integer.MIN_VALUE ) ;
			this.adj_list[ i ] = new ArrayList< Integer >() ;
		}
	}
	
	private void incrementInd() {
		this.ind++ ;
	}
	
	public void setCn( int c ) {
		this.cn = c ;  
	}
	
	public void incrementCn() {
		this.cn++ ;
	}
	
	public void incrementCc() {
		this.cc++ ;
	}
	
	public int getCn() {
		return this.cn ;
	}
	
	public ProblemSolver() {
		this.init() ;
	}
}

class Node implements Comparable< Node > {
	private int v , f ;
	
	private Node() {
	}
	
	public Node( int vParam , int fParam ) {
		this.v = vParam ;
		this.f = fParam ;
	}
	
	public void setV( int vParam ) {
		this.v = vParam ;
	}
	
	public void setF( int fParam ) {
		this.f = fParam ;
	}
	
	public int getV() {
		return this.v ;
	}
	
	public int getF() {
		return this.f ;
	}
	
	public int compareTo( Node nParam ) {
		return this.getV() - nParam.getV() ;
	}
}

class InputReader {
	private BufferedReader reader ;
	private StringTokenizer tokenizer ;

	public InputReader( InputStream stream ) {
		this.reader = new BufferedReader( new InputStreamReader( stream ) ) ;
		this.tokenizer = null ;
	}

	private String next( int fl ) {
		while( this.tokenizer == null || ! this.tokenizer.hasMoreTokens() ) {
			try {                
				this.tokenizer = new StringTokenizer( this.reader.readLine() ) ;
			}
			catch( IOException e ) {
				throw new RuntimeException( e ) ;
			}
		}
		String s ;
		s = "" ;
		if( fl == 1 ) {
			s = this.tokenizer.nextToken() ; 
		}
		return s ;
	}

	public String nextLine() {
		this.next( 0 ) ;
		int fl ;
		String line ;
		line = "" ;
		fl = 0 ;
		if( this.tokenizer != null ) {
			while( this.tokenizer.hasMoreTokens() ) {
				if( fl == 1 ) {
					line += " " ;
				}
				fl = 1 ;
				line += this.tokenizer.nextToken() ;
			}
		}
		return line ;
	}

	public int nextInt() {
		return Integer.parseInt( this.next( 1 ) ) ;
	}

	public long nextLong() {
		return Long.parseLong( this.next( 1 ) ) ;
	}

	public double nextDouble() {
		return Double.parseDouble( this.next( 1 ) ) ;
	}

	public String nextString() {
		return this.next( 1 ) ;
	}
}
