View Compilation Error

0_0_30948358_10823.cpp: In function 'int main()':
0_0_30948358_10823.cpp:5:2: error: expected initializer before 'scanf'
  scanf("%d %d",&a,&b);
  ^
0_0_30948358_10823.cpp:6:2: error: 'x' was not declared in this scope
  x=(a+b)/2
  ^
0_0_30948358_10823.cpp:6:7: error: 'b' was not declared in this scope
  x=(a+b)/2
       ^