View Compilation Error

0_0_30873647_18637.cpp: In function 'int main()':
0_0_30873647_18637.cpp:3:14: error: 'scanf' was not declared in this scope
 scanf("%d",&n);
              ^
0_0_30873647_18637.cpp:6:1: error: 'sum' was not declared in this scope
 sum=2+3(p-1);
 ^
0_0_30873647_18637.cpp:6:12: error: expression cannot be used as a function
 sum=2+3(p-1);
            ^
0_0_30873647_18637.cpp:7:26: error: 'printf' was not declared in this scope
 printf("%d\n",6*n*(n-1)/4);
                          ^