View Compilation Error

0_0_38779189_10338.cpp:1:1: error: 'C' does not name a type
    1 | C a[1002], b;
      | ^
0_0_38779189_10338.cpp:2:1: error: 'D' does not name a type
    2 | D ave;
      | ^
0_0_38779189_10338.cpp:3:1: error: 'I' does not name a type
    3 | I n, t, x, y, i, z, zz;
      | ^
0_0_38779189_10338.cpp:4:1: error: 'I' does not name a type
    4 | I sum, len;
      | ^
0_0_38779189_10338.cpp:5:1: error: 'I' does not name a type
    5 | I main(){
      | ^