题目不重要，我想知道为啥没有输出

#include<iostream>
#include<cstdio>
#include<algorithm>
#include <string>
using namespace std;

struct Int
{
	int a[1005];
	void operator = (string s)
	{
		a[0] = s.size();
		for (int i = 0; i < s.size(); i++)
		{
			a[a[0]-i] = s[i] - '0';
		}
		return;
	}
	Int operator + (Int B) {
		Int C;
		C.a[0] = 0;
		for (int i = 1, g = 0; ; ++i) {
			if (!g && i > a[0] && i > B.a[0])
				break;
			int x = g;
			if (i <= a[0])
				x += a[i];
			if (i <= B.a[0])
				x += B.a[i];
			C.a[++C.a[0]] = x%10;
			g = x/10;
		}
		return C;
	}

};

ostream& operator << (ostream& out, Int x)
{
	for (int i = x.a[0]; i >= 1; i--)
		out << x.a[i];
	return out;
}

istream& operator >> (istream& in, Int& x)
{
	string s;
	in >> s;
	x = s;
	return in;
}

int main() {
	int l1, r1, l2, r2;
	string s = "";
	Int a, b;
	cin >> l1 >> r1 >> l2 >> r2;
	for (int i = r1; i <= l1; i++)
	{
		int t = i;
		while (t)
		{
			s += t % 10 - '0';
			t /= 10;
		}
	}
	a = s;
	s = "";
	for (int i = r2; i <= l2; i++)
	{
		int t = i;
		while (t)
		{
			s += t % 10 - '0';
			t /= 10;
		}
	}
	b = s;
	Int c = a + b;
	cout << c;
    return 0;
}