Prince Nikolaos of Greece and Denmark (born 1 October 1969) is the third child of Constantine II and Anne-Marie of Denmark, who were the last King and Queen of Greece, reigning from 1964 to 1973.
Princess Alexia of Greece and Denmark (Greek: Αλεξία ; born 10 July 1965) is the eldest child of Constantine II and Anne-Marie of Denmark, who were the last King and Queen of Greece, reigning from 1964 to 1973.
Princess Irene of Greece and Denmark (Greek: Πριγκίπισσα Ειρήνη της Ελλάδας και Δανίας ; born 11 May 1942) is the youngest child of King Paul of Greece and his wife Frederika of Hanover.
 She is the younger sister of Queen Sofía of Spain and of the deposed King Constantine II of Greece.
Princess Maria-Olympia of Greece and Denmark (born 25 July 1996 in New York City) is the oldest child and only daughter of Pavlos, Crown Prince of Greece and Marie-Chantal, Crown Princess of Greece.
 Her paternal grandparents are Constantine II and Anne-Marie of Denmark, who were the last King and Queen of the Hellenes.
Constantine II (Greek: Κωνσταντῖνος Β΄ , "Konstantínos II", ] ; born 2 June 1940) is a former monarch who was the last King of Greece, reigning from 1964 until the abolition of the Greek monarchy in 1973.
The Greek royal family (Greek: Ελληνική Βασιλική Οικογένεια) is a branch of the House of Glücksburg that reigned in Greece from 1863 to 1924 and again from 1935 to 1973.
 Its first monarch was George I, the second son of King Christian IX of Denmark.
 He and his successors styled themselves "Kings of the Hellenes".
 Most members of the dynasty (aside from the last king to reign, Constantine II and his queen consort, Anne-Marie of Denmark) hold the title "Prince or Princess of Greece and Denmark" with the style "Royal Highness", except Marina, Consort of Prince Michael, and their daughters Princess Alexandra and Princess Olga.
Grand Duchess Alexandra Georgievna of Russia (Russian: Алекса́ндра Гео́ргиевна ); "née" Princess Alexandra of Greece and Denmark (Greek: Πριγκίπισσα Αλεξάνδρα της Ελλάδας και της Δανίας ); 30 August 1870 – 24 September 1891) was the third child and firstborn daughter of King George I and Queen Olga of Greece, who herself was a daughter of a Russian grand duke, and was also a grandchild of Denmark's King Christian IX and Queen Louise.
 She was a sister to Constantine I of Greece, and thus aunt of three kings and two queens, Constantine's three sons, who all became kings of Greece, and two of his daughters, who were queens, in name, of Romania and Croatia, respectively.
 She was also first cousin of Tsar Nicholas II of Russia, King George V of the United Kingdom, and both King Haakon VII and Queen Maud of Norway, as well as a paternal aunt of Prince Philip, Duke of Edinburgh.
Princess Theodora of Greece and Denmark (Greek: Θεοδώρα , born 9 June 1983 in London), also known under her stage name Theodora Greece, is an actress.
 She is the younger daughter and fourth of the five children of former King Constantine II of Greece and Anne-Marie of Denmark.
Pavlos, Crown Prince of Greece, {'1': ", '2': ", '3': 'RE', '4': "} (Greek: Παύλος ; born 20 May 1967) is the eldest son and second child of Constantine II, the last King of Greece from 1964 to 1973 and his wife, Anne-Marie of Denmark.
 Pavlos was heir apparent to the throne of Greece and was its crown prince from birth, remaining so during his father's reign until the monarchy's abolition.
Princess Friederike of Hanover ("German: Friederike Elisabeth Viktoria-Luise Alice Olga Theodora Helena, Prinzessin von Hannover, Prinzessin von Großbritannien und Irland, Herzogin zu Braunschweig-Lüneburg"), (born 15 October 1954 at Salem, Baden-Württemberg, Germany) is the youngest child and only daughter of Prince George William of Hanover and his wife Princess Sophie of Greece and Denmark, sister of Prince Philip, Duke of Edinburgh.
 Queen Sofia of Spain and Constantine II of Greece are paternal first cousins and maternal first cousins once removed of Friederike, while she is a first cousin, through her mother, to Charles, Prince of Wales and a goddaughter of Elizabeth II of the United Kingdom.

Question: Princess Maria-Olympia is the only daughter of the eldest son and second child of Constantine II, who was the last king of Greece from 1964 until when?
Answer: 1973