Question: What is the current official currency in the country where the river that Lujan River turns into is located?

full_context: Document 1: Puerto Rico: Originally populated by the indigenous Taíno people, the island was claimed in 1493 by Christopher Columbus for Spain during his second voyage. Later it endured invasion attempts from the French, Dutch, and British. Four centuries of Spanish colonial government influenced the island's cultural landscapes with waves of African slaves, Canarian, and Andalusian settlers. In the Spanish Empire, Puerto Rico played a secondary, but strategic role when compared to wealthier colonies like Peru and the mainland parts of New Spain. Spain's distant administrative control continued up to the end of the 19th century, helping to produce a distinctive creole Hispanic culture and language that combined elements from the Native Americans, Africans, and Iberians. In 1898, following the Spanish -- American War, the United States acquired Puerto Rico under the terms of the Treaty of Paris. The treaty took effect on April 11, 1899.
Document 2: San Juan, Puerto Rico: San Juan is located along the north - eastern coast of Puerto Rico. It lies south of the Atlantic Ocean; north of Caguas and Trujillo Alto; east of and Guaynabo; and west of Carolina. The city occupies an area of 76.93 square miles (199.2 km), of which, 29.11 square miles (75.4 km) (37.83%) is water. San Juan's main water bodies are San Juan Bay and two natural lagoons, the Condado and San José.
Document 3: Rio de la Plata (Puerto Rico): The La Plata River () is the longest river in the island of Puerto Rico. It is located in the north coast of the island. It flows from south to north, and drains into the Atlantic Ocean about 11 miles (18 km) west of San Juan. The mouth of the river is a resort area with white sandy beaches.
Document 4: La Plata Lake: Lago La Plata is a lake located between the municipalities of Naranjito, Toa Alta, and Bayamón in Puerto Rico. The lake was created in 1973 and serves as a reservoir for potable water.
Document 5: Montevideo: Montevideo is situated on the north shore of the Río de la Plata, the arm of the Atlantic Ocean that separates the south coast of Uruguay from the north coast of Argentina; Buenos Aires lies 230 kilometres (140 mi) west on the Argentine side. The Santa Lucía River forms a natural border between Montevideo and San José Department to its west. To the city's north and east is Canelones Department, with the stream of Carrasco forming the eastern natural border. The coastline forming the city's southern border is interspersed with rocky protrusions and sandy beaches. The Bay of Montevideo forms a natural harbour, the nation's largest and one of the largest in the Southern Cone, and the finest natural port in the region, functioning as a crucial component of the Uruguayan economy and foreign trade. Various streams criss-cross the town and empty into the Bay of Montevideo. The coastline and rivers are heavily polluted and of high salinity.
Document 6: Puerto Rico: Originally populated by the indigenous Taíno people, the island was claimed in 1493 by Christopher Columbus for Spain during his second voyage. Later it endured invasion attempts from the French, Dutch, and British. Four centuries of Spanish colonial government influenced the island's cultural landscapes with waves of African slaves, Canarian, and Andalusian settlers. In the Spanish Empire, Puerto Rico played a secondary, but strategic role when compared to wealthier colonies like Peru and the mainland parts of New Spain. Spain's distant administrative control continued up to the end of the 19th century, helping to produce a distinctive creole Hispanic culture and language that combined elements from the Native Americans, Africans, and Iberians. In 1898, following the Spanish -- American War, the United States acquired Puerto Rico under the terms of the Treaty of Paris.
Document 7: Republic of Cuba (1902–1959): After the Spanish -- American War, Spain and the United States signed the Treaty of Paris (1898), by which Spain ceded Puerto Rico, the Philippines, and Guam to the United States for the sum of $20 million. Cuba gained formal independence from the U.S. on May 20, 1902, as the Republic of Cuba. Under Cuba's new constitution, the U.S. retained the right to intervene in Cuban affairs and to supervise its finances and foreign relations. Under the Platt Amendment, the U.S. leased the Guantánamo Bay naval base from Cuba.
Document 8: History of Puerto Rico: In 1898, during the Spanish -- American War, Puerto Rico was invaded and subsequently became a possession of the United States. The first years of the 20th century were marked by the struggle to obtain greater democratic rights from the United States. The Foraker Act of 1900, which established a civil government, and the Jones Act of 1917, which made Puerto Ricans U.S. citizens, paved the way for the drafting of Puerto Rico's Constitution and its approval by Congress and Puerto Rican voters in 1952. However, the political status of Puerto Rico, a Commonwealth controlled by the United States, remains an anomaly.
Document 9: Puerto Rico: Puerto Rico (Spanish for ``Rich Port ''), officially the Commonwealth of Puerto Rico (Spanish: Estado Libre Asociado de Puerto Rico, lit.`` Free Associated State of Puerto Rico'') and briefly called Porto Rico, is an unincorporated territory of the United States located in the northeast Caribbean Sea, approximately 1,000 miles (1,600 km) southeast of Miami, Florida.
Document 10: Paraguay River: The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters in the Brazilian state of Mato Grosso to its confluence with the Paraná River north of Corrientes and Resistencia.
Document 11: History of Puerto Rico: After the ratification of the Treaty of Paris of 1898, Puerto Rico came under the military control of the United States of America. This brought about significant changes: the name of the island was changed to Porto Rico (it was changed back to Puerto Rico in 1932) and the currency was changed from the Puerto Rican peso to the United States dollar. Freedom of assembly, speech, press, and religion were decreed and an eight-hour day for government employees was established. A public school system was begun and the U.S. Postal service was extended to the island. The highway system was enlarged, and bridges over the more important rivers were constructed. The government lottery was abolished, cockfighting was forbidden, and a centralized public health service established. Health conditions were poor at the time, with high rates of infant mortality and numerous endemic diseases.
Document 12: São Lourenço River (Mato Grosso): The São Lourenço River is a tributary of the Paraguay River within the Pantanal, an alluvial plain that spans portions of Brazil, Bolivia and Paraguay.
Document 13: Guajataca River: Guajataca River () is a river on the island of Lares, Puerto Rico. It is located in the northwest coast of the island. It flows from the south and drains into the Atlantic Ocean. The name was given by the original inhabitants prior to the arrival of Christopher Columbus.
Document 14: Luján River: The Luján River (Spanish, Río Luján) runs from its source near Espora about east of Buenos Aires, Argentina, to its outflow into the Río de la Plata north of the city.
Document 15: 2008 Summer Olympics torch relay: Argentina: The torch relay leg in Buenos Aires, Argentina, held on April 11, began with an artistic show at the Lola Mora amphitheatre in Costanera Sur. In the end of the show the mayor of Buenos Aires Mauricio Macri gave the torch to the first torchbearer, Carlos Espínola. The leg finished at the Buenos Aires Riding Club in the Palermo district, the last torchbearer being Gabriela Sabatini. The 13.8 km route included landmarks like the obelisk and Plaza de Mayo. The day was marked by several pro-Tibet protests, which included a giant banner reading "Free Tibet", and an alternative "human rights torch" that was lit by protesters and paraded along the route the flame was to take. Most of these protests were peaceful in nature, and the torch was not impeded. Chinese immigrants also turned out in support of the Games, but only minor scuffles were reported between both groups. Runners surrounded by rows of security carried the Olympic flame past thousands of jubilant Argentines in the most trouble-free torch relay in nearly a week. People showered the parade route with confetti as banks, government offices and businesses took an impromptu half-day holiday for the only Latin American stop on the flame's five-continent journey.
ground_truth: United States dollar
sub_queries: What river does Luján River turn into? Answer: Río de la Plata
Río de la Plata >> located in the administrative territorial entity Answer: Puerto Rico
What is the current official currency in Puerto Rico ? Answer: United States dollar