import sys
from collections import defaultdict
n = int(input())
key_num = list(map(int,sys.stdin.read().split()))
ptr = 0
total=0
hash_map=defaultdict(int)
for i in range(1,n+1):
    key=key_num[ptr]
    ptr+=1 
    num=key_num[ptr]
    ptr+=1
    #如果取不到，默认返回0
    ansi = hash_map.get(key,0)
    #重新设置hash_map[key]的值
    hash_map[key]=num

    total+=ansi*i

print(total%(2**64))