Python :

a = raw_input()
b = int(a)

if (b <2) or (b > 10):
    exit(0)

dict = {}
   
for i in range(0,b):
    k = raw_input().split()
    m  = float(k[1])
    n = float(k[2])
    o = float(k[3])
    if ( (m <0 or m>100) or (n<0 or n>100) or (o<0 or o>100) ):
        exit(0)
    dict[k[0]] = [k[1],k[2],k[3]]
last = raw_input()

print "%.2f" % round((float(dict.get(last)[0]) + float(dict.get(last)[1]) + float(dict.get(last)[2]))/3.00,2)