为啥不输出？？？？？？求助！！

#include<bits/stdc++.h>
#define int long long
using namespace std;
const int M=5e2+5;
char s[M];
char s1[M];
int s2[M];
signed main()
{
	cin>>s>>s1;
	int a[M];
	int b[M];
	int len=strlen(s);
	int len1=strlen(s1);
	for(int i=0;i<len;i++)
	{
		a[i]=s[i]-'0';
	}
	for(int i=0;i<len1;i++)
	{
		b[i]=s1[i]-'0';
	}
	for(int i=0;i<len/2;i++)
	{
		swap(a[i],a[len-1-i]);
	}
	for(int i=0;i<len1;i++)
	{
		swap(b[i],b[len1-1-i]);
	}
	int len2=max(len,len1);
	for(int i=0;i<len2;i++)
	{
		s2[i]+=a[i]+b[i];
		s2[i+1]=s2[i]/10;
		s2[i]%=10;
	} 
	if(s2[len2]!=0)
	{
		len2++;
	}
	for(int i=len2;i>1;i--)
	{
		cout<<s2[i];
	}
}