「模板」快读快写
namespace IO
{
template <typename T>
void read(T &x)
{
x = 0; bool f = 0; char c = gc();
while(!isdigit(c)) f |= c == '-', c = gc();
while(isdigit(c)) x = x * 10 + c - '0', c = gc();
if(f) x = -x;
}
template <typename T>
void write(T x)
{
if(x < 0) pc('-'), x = -x;
if(x > 9) write(x / 10);
pc('0' + x % 10);
}
}
using namespace IO;
$$A\ drop\ of\ tear\ blurs\ memories\ of\ the\ past.$$