Hello, since I'm new to Java, can anyone tell me why is this CE?


import java.math.*;
import java.io.*;
import java.util.*;

public class Main
{
      static final int MAXN = 200;
      static int n, k;
      static BigInteger DP[][] = new BigInteger[ MAXN ][ 2 ];

      public static void main(String args[])
      {
         BufferedReader f = new BufferedReader( new InputStreamReader( System.in ) );
        PrintWriter out = new PrintWriter( System.out );

        StringTokenizer st = new StringTokenizer(f.readLine());

        int n = Integer.parseInt(st.nextToken());
        int k = Integer.parseInt(st.nextToken());

        DP[ 0 ][ 0 ] = new BigInteger( "" + 1 );
        DP[ 0 ][ 1 ] = new BigInteger( "" + ( k-1 ) );

        for ( int i = 1;  i < n;  i++ )
        {
            DP[ i ][ 0 ] = DP[ i-1 ][ 1 ];
            DP[ i ][ 1 ] = ( DP[ i-1 ][ 1 ].add(DP[ i-1 ][ 0 ]) ).multiply( new BigInteger( "" + ( k-1 ) ) );
        }

        out.println( DP[ n-1 ][ 1 ] );
        out.close();
        System.exit(0);
    }
}

It says:
.\Main.java:17: unreported exception java.io.IOException; must be caught or declared to be thrown
        StringTokenizer st = new StringTokenizer(f.readLine());
                                                           ^
1 error