PAT 1031 Hello World for U

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

int main()
{
	string s;
	cin>>s;
	int len = s.size()+2;
	int n1 = len /3;
	int bottom = len - 2*n1;
	int i=0;
	for(; i<n1-1;++i)
	{
		cout<<s[i];
		for(int j=0; j<bottom-2; ++j)
		{
			cout<<" ";
		}
		cout<<s[s.size()-1-i]<<endl;
	}
	for(int k=i; k<s.size()-i; ++k)
	{
		cout<<s[k];
	}
	cout<<endl;
	return 0;
}