Adding Subtraction to a 32 bit Adder

[nnejy]

Hello, i am trying to figure out what i did wrong. i am trying to add a subtraction flag to my current 32 bit adder, and i keep getting the incorrect output back.

For example, if the user enters:
input 32 bits: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1
input 32 bits: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1
subtraction flag:0

this should be the answer:
answer:0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0

but i am instead getting:
answer:0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1

It seems the carry isn't carrying properly. I was told to set the CarryIn to the subtraction flag, which I did, but it seems to have overwritten it somehow. Any help would be greatly appreciated. Thanks for your time, code is posted below.

#include <stdio.h>

#define SIZE 32

int a[SIZE];
int b[SIZE];
int sum[SIZE];

int sflag(int a, int b, int c)
{
  return (a && !b && c);
}
int carry(int a, int b, int c)
{
  return (a && b) || (b && c) || (a && c);
}

int add(int a, int b, int c)
{
  return (a && !b && !c) || (!a && b && !c) || (!a && !b && c) || (a && b && c)\
;
}


int main()
{
  int i;
  int CarryIn;
  int flag;

  printf("input 32 bits:");
  for(i=SIZE-1;i>=0;i--)
    scanf("%d",&(a[i]));
  printf("input 32 bits:");
  for(i=SIZE-1;i>=0;i--)
    scanf("%d",&(b[i]));
  printf("subtraction flag:");
  scanf("%d", &flag);

  CarryIn = flag;

  for(i=0;i < SIZE;i++)
    {
      flag = sflag(a[i],b[i],flag);
      sum[i] = add(a[i],flag,CarryIn);
      CarryIn = carry(a[i],flag,CarryIn);
   }
  for(i=SIZE-1;i>=0;i--)
    printf("%d ",sum[i]);
  printf("\n");
   return 0;
}

[nnejy]

figured it out.