C++ __int128的使用

#include 
using namespace std;

void scan(__int128 &x) { //输入
	x = 0;
	int f = 1;
	char ch;
	if((ch = getchar()) == '-') f = -f;
	else x = x*10 + ch-'0';
	while((ch = getchar()) >= '0' && ch <= '9')
		x = x*10 + ch-'0';
	x *= f;
}

void _print(__int128 x) {
	if(x > 9) _print(x/10);
	putchar(x%10 + '0');
}
void print(__int128 x) { //输出
	if(x < 0) {
		x = -x;
		putchar('-');
	}
	_print(x);
}

int main() {
	__int128 a, b;
	scan(a);
	scan(b);
	print(a + b);
	return 0;
}