import java.util.ArrayList;
import java.util.List;

public class Simplejson {

    private String body;
    private int numItems;
    private List<String> keys = new ArrayList<String>();
    private List<String> values = new ArrayList<String>();

    public Simplejson() {
        body = "{}";
    }

    private void rebuild() {

        this.body = new String ("{");
        for(int i = 0; i < numItems; i++) {
            String key = "\"" + this.keys.get(i) + "\":";
            String value = "\"" + this.values.get(i) + "\"";
            String line = key + value;
            if(i < numItems - 1) {
                line += ",";
            }
            this.body += line;
        }
        this.body += "}";
    }

    public void add(String newKey, String newValue) {
        if(!this.keys.contains(newKey)) {
            this.keys.add(newKey);
            this.values.add(newValue);
            this.numItems++;
        }
        else {
            this.update(newKey, newValue);
        }
    }

    public void remove(String key) {
        if(this.keys.contains(key)) {
            int index = this.keys.indexOf(key);
            this.keys.remove(index);
            this.values.remove(index);
            this.numItems--;
        }
    }

    public void update(String key, String newValue) {
        if(this.keys.contains(key)) {
            int index = this.keys.indexOf(key);
            this.values.set(index, newValue);
        }
        else {
            this.add(key, newValue);
        }
    }

    public int getLength() {
        return this.numItems;
    }

    public String build() {
        this.rebuild();
        return this.body;
    }
}