How do I need to run maven file in powershell?

I assume that additional dependencies are needed, but I can not understand exactly what. I appreciate everyone's help.

My pom file is:

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.spark</groupId>
    <artifactId>spark</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
    <name>M101J</name>
    <url>http://maven.apache.org</url>

    <dependencies>
        <dependency>
            <groupId>com.sparkjava</groupId>
            <artifactId>spark-core</artifactId>
            <version>1.1.1</version>
        </dependency>

        <dependency>
            <groupId>org.freemarker</groupId>
            <artifactId>freemarker</artifactId>
            <version>2.3.19</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.6.4</version>
        </dependency>
    </dependencies>
    <repositories>
        <repository>
            <id>Spark repository</id>
            <url>http://sparkjava.com/nexus/content/repositories/spark/</url>
        </repository>
    </repositories>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-assembly-plugin</artifactId>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>com.spark.SparkHomework</mainClass>
                        </manifest>
                    </archive>
                    <descriptorRefs>
                        <descriptorRef>jar-with-dependencies</descriptorRef>
                    </descriptorRefs>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

When I try to run my project with command:

mvn compile exec:java -Dexec.mainClass=com.spark.SparkHomework

I have the issue like this:

Unknown lifecycle phase ".mainClass=com.spark.SparkHomework". You must specify a valid lifecycle phase or a goal in the format : or :[:]:. Available lifecycle phases are: validate, initialize, generate-sources, process-sources, generate-resources, process-resources, compile, process-classes, generate-test-sources, process-test-sources, generate-test-resources, process-test-resources, test-compile, process-test-classes, test, prepare-package, package, pre-integration-test, integration-test, post-integration-test, verify, install, deploy, pre-clean, clean, post-clean, pre-site, site, post-site, site-deploy.

My class named as SparkHomework (package named as com.spark) is :

package com.spark;

import freemarker.template.Configuration;
import freemarker.template.Template;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import spark.Request;
import spark.Response;
import spark.Route;
import spark.Spark;

import java.io.StringWriter;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.Map;

public class SparkHomework {
    private static final Logger logger = LoggerFactory.getLogger("logger");

    public static void main(String[] args) throws UnknownHostException {
        final Configuration configuration = new Configuration();
        configuration.setClassForTemplateLoading(
                SparkHomework.class, "/");

        Spark.get(new Route("/") {
            @Override
            public Object handle(final Request request,
                                 final Response response) {
                StringWriter writer = new StringWriter();
                try {
                    Template helloTemplate = configuration.getTemplate("answer.ftl");

                    Map<String, String> answerMap = new HashMap<String, String>();
                    answerMap.put("answer", createAnswer());

                    helloTemplate.process(answerMap, writer);
                } catch (Exception e) {
                    logger.error("Failed", e);
                    halt(500);
                }
                return writer;
            }
        });
    }


    private static String createAnswer() {
        int i = 0;
        for (int bit = 0; bit < 16; bit++) {
            i |= bit << bit;
        }
        return Integer.toString(i);
    }
}