`@` 6,5

#include <iostream>
#include <string>
using namespace std;
int main()
{
string s, s1="";
getline(cin,s);
for (int i=s.length()-1; i>=0; i--)
s1=s1+s[i];
if (s1==s)
cout<<"YES";
else
cout<<"NO";
return 0;
}

`@` 6,6

#include <iostream>
#include <cmath>
using namespace std;
int main() {
long long x,t,k;
int i;
cin>>x;
t=0;
while (x!=0) {
k=x%10;
x/=10;
t+=k;
}
cout<<t<<endl;
return 0;
}

`@`6,7

#include <iostream>
#include <string>
#include <sstream>
using namespace std;
int main() {
string s;
getline(cin,s);
int d=0;
stringstream ss(s);
string word;
while (ss>>word) {
d++;
}
cout<<d<<endl;
return 0;
}