#import<iostream>
using namespace std;

string h(string a, string b, int lena, int lenb) {
	for (int i = 0; i < lena - lenb; i++)
		b.insert(0, "0");
	return b;
}

main() {
	string a, b;
	cin >> a >> b;
	int c[1005] = {0}, ks = 0, lena = a.size(), lenb = b.size();
	if (lena > lenb)
		b = h(a, b, lena, lenb);
	else
		a = h(b, a, lenb, lena);
	for (int i = a.size() - 1; i >= 0; i--) {
		c[i] = ((a[i] - '0') + (b[i] - '0') + c[i + 1]) / 10;
		c[i + 1] = ((a[i] - '0') + (b[i] - '0') + c[i + 1]) % 10;
	}
	if (c[0] == 0)
		ks = 1;
	for (int i = ks; i < a.size() + 1; i++)
		cout << c[i];
}

求助