You are given several queries. In the i-th query you are given a single positive integer ni. You are to represent ni as a sum of maximum possible number of composite summands and print this maximum number, or print -1, if there are no such splittings.
An integer greater than 1 is composite, if it is not prime, i.e. if it has positive divisors not equal to 1 and the integer itself.
The first line contains single integer q (1 ≤ q ≤ 105) — the number of queries.
q lines follow. The (i + 1)-th line contains single integer ni (1 ≤ ni ≤ 109) — the i-th query.
For each query print the maximum possible number of summands in a valid splitting to composite summands, or -1, if there are no such splittings.
1 12
3
2 6 8
1 2
3 1 2 3
-1 -1 -1
12 = 4 + 4 + 4 = 4 + 8 = 6 + 6 = 12, but the first splitting has the maximum possible number of summands.
8 = 4 + 4, 6 can't be split into several composite summands.
1, 2, 3 are less than any composite number, so they do not have valid splittings.
题意 将一个数分为若干个合数 求出最多可以有多少个
例
4 》 4 = 1(本身也是合数)
5 = -1(本身不是合数)
6 》 6 = 1
7 = -1
8 》 4,4 = 2
9 》 9 = 1
19 》 4,6,9 = 3
小于12的数特判
对于大于等于12的数n:
找到的规律是 让n对最小的合数4取余
n%4==0 输出n/4
n%4==1,1与两个4结合成9 也就是输出n/4-1
n%4==2,2与一个4结合成6,也就是输出n/4
n%4==3,三拆为1+2,1与两个结合为9,2与一个4结合为6,也就是输出n/4-1
#include <cstdio>
#include <cstring>
#include <string>
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int n, m;
scanf("%d", &n);
for (int i = 0; i < n; i ++) {
scanf("%d", &m);
if (m == 1 || m == 2 || m == 3 || m == 5 || m == 7 || m == 11) {
printf("-1\n");
}
else if (m % 4 == 0) {
printf("%d\n", m / 4);
}
else if (m % 4 == 1 || m % 4 == 3) {
printf("%d\n", m / 4 - 1);
}
else if (m % 4 == 2) {
printf("%d\n", m / 4);
}
}
}