Skype, Google talk... and Microphone? Not necessary:-)

In our days programmers often use programs like Skype, Google talk, MSN, etc for conference calls. In order to participate in the call you need:
1. Computer with one of the program installed on it.
2. Internet.
3. Speakers.
4. Microphone.

But what to do if somebody already calling to you but you don't have microphone? How many of you tried to shout to your computer in hope that it has embedded microphone? :-). Solution was very close. In situation like that you just need to plug in another earphones in a plughole for microphone and talk to left earphone. Keep it very close to your mouse and also you may need to put microphone volume on maximum. For urgent call the quality of sound is very very acceptable but if you consider to have a long relationship with somebody on other end of the internet consider to buy a good microphone.

int* p=0;

There is a little program:
#include
int main(){
int* p=0;
p++;
printf("%u\n", p);
return 0;
}
The output is: 4
and the program runs without mistakes and warnings.
But why I couldn't run the next one?

#include
int main(){
int* p=4;
printf("%u\n", p);
return 0;
}

in other words my question would be:
How to make p=4 at one stroke?