nested list in hackerrank
d={} #1
for _ in range(int(raw_input())): #2
Name=raw_input() #3
Grade=float(raw_input()) #4
d[Name]=Grade #5
v=d.values()#6
second=sorted(list(set(v)))[1] #7
second_lowest=[] #8
for key,value in d.items(): #9
if value==second: #10
second_lowest.append(key) #11
second_lowest.sort() #12
for name in second_lowest: #13
print name #14