View Compilation Error

0_0_37705487_29174.cpp: In function 'int main()':
0_0_37705487_29174.cpp:9:22: error: expected ')' before numeric constant
         sum=n%2 ? (n 1)/2*n : n/2*(n 1);
                      ^
0_0_37705487_29174.cpp:9:40: error: expected ':' before ';' token
         sum=n%2 ? (n 1)/2*n : n/2*(n 1);
                                        ^
0_0_37705487_29174.cpp:9:40: error: expected primary-expression before ';' token