import sys
from collections import defaultdict

l1 = []
l2 = defaultdict(int)

for l in sys.stdin:
    l = [int(x) for x in l.split()]
    l1.append(l[0])
    l2[l[1]] += 1

s = 0
for i in range(len(l1)):
    s += l1[i] * l2[l1[i]]

print(s)