Diego is married to Consuela, who lives with him. Both are U.S. citizens and residents of Nebraska. Diego furnishes all of the support of his parents, who are citizens and residents of Mexico. He also furnishes all of the support of Consuelas parents, who are citizens and residents of El Salvador. All of their parents had no gross income for the 2019 tax year. If Diego and Consuela file a joint tax return in 2019, how dependents can they claim on the joint return?