View Compilation Error

0_0_33874479_30886.cpp: In function 'void MC()':
0_0_33874479_30886.cpp:201:22: error: 'id' was not declared in this scope
    int r=x,l=size[ch[id][0]]+1;  //找到 1-r中第一个小于y的位置 
                      ^