BOJ - 14730 - 謎紛芥索紀 (Small)

import sys

def solution():
    N = int(input())
    ret = 0
    for _ in range(N):
        C, K = map(int, sys.stdin.readline().split())
        ret += C * K
    print(ret)
solution()

https://www.acmicpc.net/problem/14730