codeforces 390B Inna, Dima and Song

                                                                                                   B. Inna, Dima and Song

                                                                                    time limit per test            1 second

                                                                                    memory limit per test        256 megabytes

input

standard input

output

standard output

Inna is a great piano player and Dima is a modest guitar player. Dima has recently written a song and they want to play it together. Of course, Sereja wants to listen to the song very much.

A song is a sequence of notes. Dima and Inna want to play each note at the same time. At that, they can play thei-th note at volume v (1 ≤ v ≤ a_i;v is an integer) both on the piano and the guitar. They should retain harmony, so the total volume with which thei-th note was played on the guitar and the piano must equalb_i. If Dima and Inna cannot play a note by the described rules, they skip it and Sereja's joy drops by 1. But if Inna and Dima play thei-th note at volumes x_i andy_i(x_i + y_i = b_i) correspondingly, Sereja's joy rises by x_i·y_i.

Sereja has just returned home from the university and his current joy is 0. Help Dima and Inna play the song so as to maximize Sereja's total joy after listening to the whole song!

Input

The first line of the input contains integer n(1 ≤ n ≤ 10⁵) — the number of notes in the song. The second line containsn integers a_i(1 ≤ a_i ≤ 10⁶). The third line containsn integers b_i(1 ≤ b_i ≤ 10⁶).

Output

In a single line print an integer — the maximum possible joy Sereja feels after he listens to a song.

Sample test(s)

Input

31 1 22 2 3

Output

4

Input

125

Output

-1

Note

In the first sample, Dima and Inna play the first two notes at volume 1 (1 + 1 = 2, the condition holds), they should play the last note at volumes1 and 2. Sereja's total joy equals:1·1 + 1·1 + 1·2 = 4.

In the second sample, there is no such pair (x, y), that1 ≤ x, y ≤ 2, x + y = 5, so Dima and Inna skip a note. Sereja's total joy equals -1.

解题思路：一组组跑就行，注意会超int，用long long存

题目链接：http://codeforces.com/problemset/problem/390/B

代码：

#include <iostream>#include <stdio.h>using namespace std;int a[1000010];    int b[1000010];int main(){    int n;    while(scanf("%d",&n)!=EOF)    {        for(int i=0;i<n;i++)        scanf("%d",&a[i]);        for(int i=0;i<n;i++)        scanf("%d",&b[i]);        long long ans=0;        for(int i=0;i<n;i++)        {            if(b[i]==1||a[i]*2<b[i])            ans--;            else            {                long long cmp=b[i]/2;                long long cmp1=b[i]-cmp;                ans+=(cmp*cmp1);            }        }        cout<<ans<<endl;    }    return 0;}