Question:
Which employer did José Joaquín de Olmedo work for in Jan, 1819?

Context:
 José Joaquín de Olmedo works for National University of San Marcos from Jan, 1808 to Aug, 1808. 
 José Joaquín de Olmedo works for Vicente Ramón Roca from Jan, 1819 to Jan, 1819. 
 José Joaquín de Olmedo works for Gran Colombia from Jan, 1825 to Jan, 1830. 
 José Joaquín de Olmedo works for Provincia Libre de Guayaquil from Oct, 1820 to Jul, 1822. 
 José Joaquín de Olmedo works for Real Convictorio de San Carlos from Jan, 1800 to Jan, 1808. 
 José Joaquín de Olmedo works for Constituent Congress of Peru, 1822 from Sep, 1822 to Mar, 1825. 
 José Joaquín de Olmedo works for Cádiz Cortes from Sep, 1810 to May, 1814. 
 José Joaquín de Olmedo works for Government of Ecuador from Jan, 1845 to Jan, 1845. 
 José Joaquín de Olmedo works for Municipality of Guayaquil from Jan, 1838 to Jan, 1840.

Answer:
Vicente Ramón Roca