View Compilation Error

0_0_28550663_13632.cpp: In function 'int main()':
0_0_28550663_13632.cpp:57:9: error: 'a' was not declared in this scope
   sum=0;a
         ^
0_0_28550663_13632.cpp:58:22: error: expected ';' before ')' token
   for(i=0;i<lun-1;i++){
                      ^
0_0_28550663_13632.cpp:77:1: error: expected '}' at end of input
 }
 ^
0_0_28550663_13632.cpp:77:1: error: expected '}' at end of input