View Compilation Error

0_0_32439311_15151.cpp: In function 'void change(char*)':
0_0_32439311_15151.cpp:9:2: error: 'cout' was not declared in this scope
  cout<<str[i];
  ^
0_0_32439311_15151.cpp:10:2: error: 'cout' was not declared in this scope
  cout<<endl;
  ^
0_0_32439311_15151.cpp:10:8: error: 'endl' was not declared in this scope
  cout<<endl;
        ^
0_0_32439311_15151.cpp: In function 'int main()':
0_0_32439311_15151.cpp:16:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_32439311_15151.cpp:20:11: error: 'gets' was not declared in this scope
   gets(str);
           ^