AC

#include<bits/stdc++.h>
using namespace std;
int a[105],b[105],c[105];
string s1,s2;
int l1,l2;
int main(){
	cin >> s1 >> s2;
	l1 = s1.length();
	l2 = s2.length();
	for(int i=0;i<l1;i++) a[l1-i] = s1[i] - '0';
	for(int i=0;i<l2;i++) b[l2-i] = s2[i] - '0';
	int l = max(l1,l2);
	for(int i=1;i<=l;i++){
		c[i] += a[i] + b[i];
		if(c[i]>9){
			c[i+1] = 1;
			c[i] %= 10;
		}
	}
	if(c[l+1]) l++; 
	for(int i=l;i>=1;i--) cout << c[i];
	return 0;
}