View Compilation Error

0_0_37135789_22622.cpp:2:2: error: expected unqualified-id before numeric constant
  2 using namespace std;
  ^
0_0_37135789_22622.cpp:3:2: error: expected unqualified-id before numeric constant
  3 unsigned int judge(int n);
  ^
0_0_37135789_22622.cpp:4:2: error: expected unqualified-id before numeric constant
  4 int main(void)
  ^