UOJ的题目好多，练习好全面，数据好强大。

#include <cstdio>
int main()
{
  printf("Hello UOJ!");
  return 0;
}

$ 2 h_x+d_x+ \ldots + d_{y-1} +2 h_y =2 h_x- \left( d_1+d_2+ \ldots + d_{x-1} \right) + 2 h_y+ \left( d_1 + d_2 + \ldots + d_{y-1} \right) $

$ R_y=2 h_y+ \left( d_1 + d_2 + \ldots + d_{y-1} \right)=2 h_y +\sum _{i=1}^{y-1}d_{i} $

$ L_x=2 h_x- \left( d_1+d_2+ \ldots + d_{x-1} \right)=2 h_x -\sum _{i=1}^{x-1}d_{i} $