题解 | 小红的合数寻找

#include <iostream>
using namespace std;
#define I int
#define LL long long

void findPri() ;

int main() {
	findPri() ;

	return 0;
}


void findPri() { //小红的合数寻找
//https://www.nowcoder.com/practice/2a35a6306f204ea3ab76ff10d188ff9e?channelPut=w25springcamp
	I x;
	cin >> x;
	if (x == 1)
		cout << -1;
	else
		cout << 2 * x;
}