How to solve error cout undeclared and cin undeclared in Dev c++

If your using Dev c++ as compiler for c++ program but you getting following error.

`cin' undeclared (first use this function)
`cout' undeclared (first use this function)

Than use following statement after header files.

using namespace std;

see following example to get idea

#include
int main()
{
int num;
cin>> num;
cout << num; return 0; } modify this program by adding using namespace std; statement. #include
using namespace std;
int main()
{
int num;
cin>> num;
cout << num;
return 0;
}