80分求助

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

int main()
{
	 string s; 
	 cin >> s;
	 string sFriend;
	 sFriend.length() == s.length();
	 for(int i = 0; i < s.length()-1; i++)
	 {
	 	sFriend[i] = s[i]+s[i+1];
	 	cout << (char)sFriend[i];
	 }
	 	 sFriend[s.length()-1] = s[s.length()-1] +s[0];
	 cout << (char)sFriend[s.length()-1] << endl;
	
	
	system("pause");
	return 0;
}