#include<stdio.h>
#include<math.h>

int add(int input1,int input2);
int mul(int input1,int input2);
int div(int input1,int input2);
void bin(int input1);
int overflow;

void main()
{
		overflow=0;
		int a1,a2;
		int cal;
		int result;
		printf("what's your operation?\n1-add/ 2-subtract/ 3-multiply/ 4-divide / 5-binary\n");
		scanf("%d",&cal);
		printf("first number");
		scanf("%d",&a1);
		if(cal==5)
		 {
			 bin(a1);
		}
		else{
			printf("second number");
			scanf("%d",&a2);
		switch(cal)
		{
		case 1:
ADD:
			result=add(a1,a2);
			break;
		case 2:
			a2=~a2;
			a2=add(a2,1);
			goto ADD;
		case 3:
			result=mul(a1,a2);
			break;
		case 4:
			result=div(a1,a2);
		break;
		}

		if(overflow==1)
			printf("overflow\n");
		else
			printf("%d",result);
		}
}

 

int add(int input1,int input2)
{
	int now=input1;
	int cin=input2;
	int cout=0;
	do{

		cout = cin&now;
		now = cin^now;
		cin = cout<<1;

	}while(cout!=0);

	if((input1^input2)>0)
		if((input1^now)<0)
			overflow=1;

	return now;
}

int mul(int input1,int input2)
{
	int sum=0;
	int temp;
	int sumtemp;
	if(input2<0)
	{
		input2=abs(input2);
		input1=~input1;
		input1=add(input1,1);
	}

	if((input2&1)==1)
	{
		sum=~input1;
		sum=add(sum,1);
	}
	goto START;

	do
	{
     
		sumtemp=input1<<1;
		if((sumtemp^input1)<0)
		{
			if(input2==1)
			{
				sum=add(sum,input1);
				sum=add(sum,input1);
			}
			else
				overflow=1;
			break;
		}
		temp=input2&3;

		if(temp==1)
			goto ADD;
		else if(temp!=2)
			goto NEXT;

		sumtemp=~sumtemp;
		sumtemp=add(sumtemp,1);

ADD :
		sum=add(sum,sumtemp); 
NEXT :
		input2=input2>>1;
		input1=input1<<1;
		
START : ; 

	}while(input2!=0);

	return sum;
}

int div(int input1,int input2)
{

	int sign=0;
	int rem=0;
	sign=(input1^input2)<0;
	input1=abs(input1);
	input2=abs(input2);
	int copy=~input2;
	copy=add(copy,1);

	int temp;
	goto START;
    do{
        input2=temp;
 
START: 
		temp=input2<<1;
        if(temp<0)
			break;
	}while(input1>temp);
	input2=~input2;
	input2=add(input2,1);
    
	goto START2;
	do
	{
		rem=rem<<1;
		input2=input2>>1;
START2: 
		temp=add(input1,input2);
		if(temp>=0)
		{
			rem=rem|1;
			input1=temp;
		}


	}while(input2!=copy);

	if(sign==1)
	{
		rem=~rem;
		rem=add(rem,1);
	}
	return rem;
}



void bin(int input1)
{
	int temp;
	int pointer=1;
	goto START;
    do{
        pointer=temp;
 
 START: temp=pointer<<1;
        if(temp<0)
        break;
    }while(input1>=temp);
  
	do{
		if((input1&pointer)==pointer)
			printf("1");
		else
			printf("0");
	pointer=pointer>>1;
	}while(pointer!=0);
}