practica 2.18

Practica graficos-> https://docs.google.com/spreadsheet/ccc?key=0AkaVifvMzBeGdFNWeERReU5rU1VSV1drT0pfYnF5a2c&hl=en_US#gid=6

Practica tesoro -> https://docs.google.com/spreadsheet/ccc?key=0AkaVifvMzBeGdHBJSWNZOVVGMkF6V1BxX2x1cTZyT0E&hl=en_US#gid=0