you have the file infile.txt contaning the data for 40 students like:

sid g1 g2 g3 123 70 80 90 234 60 80 70 321 40 50 60

write python code to read the data from that file, then calculate arithmetic average of g1,g2 and g3 for each student. and strore in a dictionary with the keys as sid and values are average of each student, like: av={123:80, 234:70, 321:50, ...}