import sys;
f = open(sys.argv[1], 'r');
NORMAL=0;
CLEAR=1;
mode = NORMAL;
for ln in f:
    if("begin_student_code" in ln):
        mode = CLEAR;
    if(mode==NORMAL): 
        sys.stdout.write(ln);
    if(mode==CLEAR and "///" in ln):
        sys.stdout.write(ln.replace("///", "",1));
    if("end_student_code" in ln):
        mode = NORMAL;