Fast Math test case

This is my code for the fast math problem. I scored 50/100. I have checked all the possible test cases. I’ve accounted for negative numbers and I’m printing the leading 0s as well. Can you give me a test case for which this code won’t work?

#include
#include
using namespace std;
#define ll long long
int main() {
ll tc;
cin>>tc;
while(tc–)
{
string m, n;
ll a,b;
cin>>m>>n;
ll l = m.length();

	a = stoi(m);
	b = stoi(n);
    
    if(a<0)
    {
        l--;
    }
    a = abs(a);
    b = abs(b);
	ll x,y;
    ll arr[l],i;
    for(i=0;i<l;i++)
    {
        arr[i]=0;
    }
	for(i=l-1;i>=0;i--)
	{
		x = a%10;
		y = b%10;
		arr[i] = x^y;
		a = a/10;
		b = b/10;
	}
	for(i=0;i<l;i++)
	{
		cout<<arr[i];
	}
	cout<<endl;
}
return 0;

}

hello @asht00 the error in your code is this it is a string question you should not contaon the whole number to integer becuase of there is string of length 20 then it would give you a number of 20 digits which GCC compler cannot handle .
that why you should do the code for this question by string only.
here for your reference i am attaching the correct code .


i hope i have cleared your doubt .
Happy Learning !!