View Compilation Error

0_0_36718493_6856.cpp: In function 'void dfs(int, int, int)':
0_0_36718493_6856.cpp:41:4: error: 'u' was not declared in this scope
 fa[u][i]=fa[fa[u][i-1]][i-1];
    ^
0_0_36718493_6856.cpp: In function 'int query(int, int, int, int, int)':
0_0_36718493_6856.cpp:88:25: error: 'o' was not declared in this scope
 if(x<=mid)res+=query(ls[o],l,mid,x,y);
                         ^
0_0_36718493_6856.cpp:89:24: error: 'o' was not declared in this scope
 if(y>mid)res+=query(rs[o],mid+1,r,x,y);
                        ^