#include <string>
#include <iostream>
 
using namespace std;
int main()
{
    string a;
    getline(cin, a);
 
    size_t first_start = 0;
    size_t first_len = a.find(' ');
 
    size_t last_start = a.rfind(' ') + 1;
    size_t last_len = a.size() - last_start;
 
    size_t mid_start = first_len;
    size_t mid_len = last_start - first_len;
 
    string b = a.substr(last_start, last_len)
             + a.substr(mid_start, mid_len)
             + a.substr(first_start, first_len);
 
    std::cout << b << '\n';
}
 

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

VGhpcyBpcyBhbiBleGFtcGxlIG9mIHRoYXQgcHJvZ3JhbSB0aGF0IHN3YXBzIGZpcnN0IGFuZCBsYXN0IHdvcmQu

This is an example of that program that swaps first and last word.