球球大佬们看看哪里有问题

#include<iostream>
#include<string>1
using namespace std;
int main()
{
	char  a[55] = { 0 };
	int n;
	string s;
	int x;
	cin >> n;
	cin >> s;
	for (int i = 0; i < s.size(); i++) 
	{
		if (s[i] == 'z')
			s[i] = 'a';
		else
		{
			if (int(s[i] + n) > 122)
			{
				x = int(s[i] + n - 'z');
				s[i] = 'a' + x - 1;
			}
			else
				s[i] = char(s[i] + n);
		}
	}
   cout<<s;
	return 0;
}