警示后人：实数输入可能没有小数点

pii Fread() {
	int x = 0; char ch = gc();
	while (!isdigit(ch)) {
		if (ch < 10) exit(0); 
		ch = gc();
	}
	int flt = -1;
	while (isdigit(ch) || ch == '.') {
		if(~flt) flt++;
		if(ch == '.') flt = 0/**/, ch = gc();
		else x = x * 10 + (ch ^ 48), ch = gc();
	}
	if(!x) return pii(514514, 1919810);
	pii ret = pii(-flt, -flt);
	while(!(x & 1)) x >>= 1, ret.x++;
	while(x % 5 == 0) x /= 5, ret.y++;
	return ret;
}