"Operation not permitted"

#include <stdio.h>
#include <stdlib.h>
#include "tested_declarations.h"
#include "rdebug.h"

int add(const int *first, const int *second, int* result)
{
     if(first == NULL || second == NULL)
      return 1;
    *result=*first+*second;
    return 0;

}
int subtract(const int *first, const int *second, int* result)
{
    if(first == NULL || second == NULL)
      return 1;
    *result=*first+*second;
    return 0;

}
int multiply(const int *first, const int *second, int* result)
{
    if(first == NULL || second == NULL)
      return 1;
    *result=*first+*second;
    return 0;

}
int divide(const int *first, const int *second, float* result)
{
    if(first == NULL || second == NULL || second==0)
      return 1;
    else
    {
        *result=(*first)/(*second);
        return 0;
    }
}

int main()
{
    int a,b,result;
    int *pa,*pb,*pc;
    pa=&a,pb=&b,pc=&result;
    char *znak;
    char kurwa;
    znak=&kurwa;
    printf("Podaj dzialanie:");
    if(scanf("%d",pa)==1)
    {
        scanf("%c",znak);
        if(scanf("%d",pb)==1)
        {
            if(*znak=='+')
            {
                if(add(pa,pb,pc)==0)
                    printf("%d",*pc);
                else
                {
                    printf("Operation not permitted");
                    return 4;
                }
            }
            else if(*znak=='-')
            {
                 if(subtract(pa,pb,pc)==0) printf("%d",*pc);
                else
                {
                    printf("Operation not permitted");
                    return 4;
                }
            }
            else if(*znak=='*')
            {
                 if(multiply(pa,pb,pc)==0) printf("%d",*pc);
                else
                {
                    printf("Operation not permitted");
                    return 4;
                }
            }
            else if(*znak=='/')
            {
                 if(divide(pa,pb,pc)==0)
                    printf("%d",*pc);
                else
                {
                    printf("Operation not permitted");
                    return 4;
                }
            }
        }
        else
        {
            printf("Incorrect input");
            return 1;
        }

    }
    else
    {
        printf("Incorrect input");
        return 1;
    }

return 0;
}