What was the change in the gross profit between the quarters of January 26 and April 27, 2018?
{"Net revenues": {"July 28, 2017": 1321.0, "October 27, 2017": 1415.0, "January 26, 2018": 1539.0, "April 27, 2018": 1644.0}, "Gross profit": {"July 28, 2017": 824.0, "October 27, 2017": 900.0, "January 26, 2018": 956.0, "April 27, 2018": 1029.0}, "Provision for income taxes (1)": {"July 28, 2017": 14.0, "October 27, 2017": 48.0, "January 26, 2018": 983.0, "April 27, 2018": 38.0}, "Net income (loss)": {"July 28, 2017": 131.0, "October 27, 2017": 174.0, "January 26, 2018": -479.0, "April 27, 2018": 290.0}, "Net income (loss) per share, basic": {"July 28, 2017": 0.49, "October 27, 2017": 0.65, "January 26, 2018": -1.79, "April 27, 2018": 1.09}, "Net income (loss) per share, diluted": {"July 28, 2017": 0.47, "October 27, 2017": 0.63, "January 26, 2018": -1.79, "April 27, 2018": 1.06}}
gross_profit_april_27_2018 = df["Gross profit"]["April 27, 2018"]
gross_profit_january_26_2018 = df["Gross profit"]["January 26, 2018"]
answer = gross_profit_april_27_2018 - gross_profit_january_26_2018