快读快写
inline int read() { int x = 0, w = 0; char ch = 0; while (!isdigit(ch)) {w |= ch == '-'; ch = getchar();} while (isdigit(ch)) {x = (x << 3) + (x << 1) + (ch ^ 48); ch = getchar();} return w ? -x : x; }
inline void write(int x) { if (x < 0) putchar('-'), x = -x; if (x > 9) write(x / 10); putchar(x % 10 + '0'); }