Eu sou um usuário do Linux Mint 15.
Eu queria escrever um programa simples em C.
Abaixo está o meu código (hw.c)

#include<stdio.h>
#include<conio.h>
int main()
{
    printf("Hello World");
}

Mas, quando eu tento compilá-lo com o gcc

gcc -o hw hw.c

isso me dá um erro

hw.c:1:18: fatal error: stdio.h: No such file or directory
compilation terminated.

Eu pesquisei e encontrei algumas soluções que dizem para instalarbuild-essential
e tentei instalar

sudo apt-get install build-essintial

mas dá um erro novamente. O erro é

    Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 build-essential : Depends: libc6-dev but it is not going to be installed or
                            libc-dev
                   Depends: g++ (>= 4:4.4.3) but it is not going to be installed
                   Depends: dpkg-dev (>= 1.13.5) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Então, o que está errado? Qual é o problema?
Como resolver isso?

PS. O resultado delocate stdio.h é

/usr/lib/perl/5.14.2/CORE/nostdio.h
/usr/lib/syslinux/com32/include/stdio.h