struct BigNumber diff(struct BigNumber m, struct BigNumber k)
{
	int comp,i;
	struct BigNumber answ;
	if(m.sign==k.sign)
	{
		if(m.sign==0)
		{
			comp=compareAbs(m,k);
			if(comp==1)
			{
				answ=diff_maincase(m,k);
				if(answ.sign==1)
				{
					printf("-");
				}
				for(i=answ.length-1;i>-1;i--)
				{
					printf("%c",answ.value[i]);
				}
				return answ;
			}
			if(comp==-1)
			{
				answ=diff(k,m);
				answ.sign=1-answ.sign;
				if(answ.sign==1)
				{
					printf("-");
				}
				for(i=answ.length-1;i>-1;i--)
				{
					printf("%c",answ.value[i]);
				}
				return answ;
			}
			if(comp==0)
			{
				answ.sign=0;
				answ.length=1;
				answ.value[0]='0';
				if(answ.sign==1)
				{
					printf("-");
				}
				for(i=answ.length-1;i>-1;i--)
				{
					printf("%c",answ.value[i]);
				}
				return answ;
			}
		}
		if(m.sign==1)
		{
			m.sign=0;
			k.sign=0;
			answ=diff(m,k);
			answ.sign=1-answ.sign;
			return answ;
		}
	}
	if(m.sign!=k.sign)
	{
		if(m.sign==0)
		{
			k.sign=0;
			return sum(m,k);
		}
		if(m.sign==1)
		{
			m.sign=0;
			answ=sum(m,k);
			answ.sign=1-answ.sign;
			return answ;
		}
	}
}

struct BigNumber diff_maincase(struct BigNumber m, struct BigNumber k)
{
	int i,j,x=0,y;
	struct BigNumber answ;
	answ.sign=0;
	answ.length=0;
	for(i=0;i<k.length;i++)
	{
		y=m.value[i]-k.value[i]-x;
		if(y>=0)
		{
			answ.value[i]='0'+y;
		}
		else
		{
			x=1;
			answ.value[i]='0'+10-y;
		}
		printf("%c ",answ.value[i]);
	}
	for(i=k.length-1,j=0;i>=0;i--,j++)
	{
		if(answ.value[i]!='0')
		{
			break;
		}
	}
	if(i<=0)
	{
		answ.length=1;
	}
	answ.length=m.length-j;
	return answ;
}

struct BigNumber sum(struct BigNumber m, struct BigNumber k)
{
	int comp;
	struct BigNumber answ;
	if(m.sign==k.sign)
	{
		if(m.sign==0)
		{
			comp=compareAbs(m,k);
			if(comp==1)
			{
				return sum_maincase(m,k);
			}
			if(comp==-1)
			{
				return sum_maincase(k,m);
			}
			if(comp==0)
			{
				return sum_maincase(m,k);
			}
		}
		if(m.sign==1)
		{
			m.sign=0;
			k.sign=0;
			answ=sum(m,k);
			answ.sign=1-answ.sign;
			return answ;
		}
	}
	if(m.sign!=k.sign)
	{
		k.sign=1-k.sign;
		return diff(m,k);
	}
}

struct BigNumber sum_maincase(struct BigNumber m, struct BigNumber k)
{
	int i,x=0;
	struct BigNumber answ;
	answ.sign=0;
	answ.length=0;
	for(i=0;i<k.length;i++)
	{
		if(-'0'+m.value[i]+k.value[i]+x<='9')
		{
			answ.value[i]='0'+m.value[i]-'0'+k.value[i]-'0'+x;
			x=0;
		}
		else
		{
			answ.value[i]=-'0'+m.value[i]+k.value[i]+x-10;
			x=1;
		}
	}
	answ.length=m.length;
	if(x!=0)
	{
		answ.value[i]='1';
		answ.length++;
	}
	return answ;
}