View Compilation Error

0_0_33742192_14446.cpp: In function 'void add()':
0_0_33742192_14446.cpp:47:20: error: 'sqn' was not declared in this scope
   block[a].l=(a-1)*sqn+1;
                    ^
0_0_33742192_14446.cpp:53:20: error: 'sqn' was not declared in this scope
   address[a]=(a+1)/sqn;
                    ^
0_0_33742192_14446.cpp: In function 'int main()':
0_0_33742192_14446.cpp:183:3: error: 'sqn' was not declared in this scope
   sqn=sqrt(n);
   ^