View Compilation Error

0_0_16234478_752.cpp: In function 'int main()':
0_0_16234478_752.cpp:5:31: error: 'long long' invalid for 'SUM'
         long long double SUM(n);
                               ^
0_0_16234478_752.cpp:5:30: error: 'n' was not declared in this scope
         long long double SUM(n);
                              ^
0_0_16234478_752.cpp:6:33: error: 'SUM' cannot be used as a function
         while(scanf("%lf",&SUM(n))!=EOF)
                                 ^
0_0_16234478_752.cpp:8:38: error: 'SUM' cannot be used as a function
                 printf("%lf\n",(SUM(n)*(SUM(n)+1))/2);
                                      ^
0_0_16234478_752.cpp:8:46: error: 'SUM' cannot be used as a function
                 printf("%lf\n",(SUM(n)*(SUM(n)+1))/2);
                                              ^