char *search( k, pat, text )
     int k;
     char *pat, *text;

     { int j, m, count;

       m = strlen(pat);
       if( m <= k ) return( text );

       for( ; *text != EOS; text++ ) {
          for( count=j=0; j < m && count <= k; j++ )
               if( pat[j] != text[j] ) count++;
          if( count <= k ) return( text );
          }

       return( NULL );
     }