[c] getting the error: expected identifier or ‘(’ before ‘{’ token

Getting this error : expected identifier or ‘(’ before ‘{’ token on the first bracket after the #include before the int main. No clue why! Doing an assignment for an introductory programming course. It's due today so any help would be appreciated!

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
{
int main(void);

int cardNum(int firstCard, int secondCard; 
int highLow;
int score;

score = 0;   
srand(time(NULL));

    printf("The current card is a %d\n" ,firstCard(2,14));
    printf("\n Will the next card be higher(1) or lower(2)? (press 0 to quit)");
    scanf("%d" ,highLow);
if cardNum > 1 && cardNum < 11
{        
     printf ("The card is: %d ,secondCard.");
}        
else if cardNum == 11
{
if highLow == 1, && secondCard > firstCard OR highLow == 2, && secondCard < firstCard
    {   
        score = score + 1; 
        printf ("\n You have guessed correctly.");
        printf ("\n Your current score is %d ,score!\n");
        printf("The current card is a ("%d" ,cardOne). \n Will the next card be           higher(1) or lower(2)? (press 0 to quit)");
    }    
else if highLow == 1, && secondCard < firstCard OR highLow == 2, && secondCard > firstCard  
    {
        score = score - 1;
        printf ("The card is: %d ,secondCard.");
        printf ("\n You have guessed incorrectly.");
        printf ("\n Your current score is %d ,score!\n");
        printf ("The current card is a %d ,cardOne."); 
        printf ("\n Will the next card be higher(1) or lower(2)? (press 0 to quit)");
    }
else if secondCard == firstCard
    {
        printf ("\n Matching cards, no change in score");
    }
else if highLow == 0
    {
        printf ("\n Thanks for playing! Your final score is %d, score.");
    }
else
    {
        printf ("\n Incorrect input. Please enter 0, 1 or 2")       
    }
}    
return(0);
}

I initially had it like that with int main(void){ but then I was getting all these errors instead so I changed it to the semicolon and only got that one error.
a3.c: In function ‘main’: a3.c:24:5: error: expected declaration specifiers or ‘...’ before ‘score’ a3.c:25:5: error: expected declaration specifiers or ‘...’ before ‘srand’ a3.c:27:5: error: expected declaration specifiers or ‘...’ before ‘printf’ a3.c:28:5: error: expected declaration specifiers or ‘...’ before ‘printf’ a3.c:29:5: error: expected declaration specifiers or ‘...’ before ‘scanf’ a3.c:31:5: error: expected declaration specifiers or ‘...’ before ‘if’ a3.c:82:1: error: expected declaration specifiers or ‘...’ before ‘}’ token a3.c:82:1: error: expected ‘;’, ‘,’ or ‘)’ before ‘}’ token a3.c:82:1: error: expected declaration or statement at end of input a3.c:82:1: warning: control reaches end of non-void function [-Wreturn-type]

you need to place the opening brace after main , not before it

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main(void)
{

{
int main(void);

should be

int main(void)
{

Then I let you fix the next compilation errors of your program...