快读快写

int read(){
  int x = 0, f = 1;
  char c = getchar();
  while (c < '0' || c > '9'){
    if (c == '-') {
      f = -1, c = getchar();
    }
  }
  while (c >= '0' && c <= '9') {
    x = x * 10 + c - '0', c = getchar();
  }
  return x * f;
}

void write(int x){
  if (x < 0) {
    putchar('-'), x = -x;
  }
  if (x > 9) {
    write(x / 10);
  }
  putchar(x % 10 + '0');
}