include <bits/stdc++.h>
using namespace std;
int main() {
string a;
int n;
getline(cin, a);
n = a.size();
int j = n - 1, i = 0, f = 0;
while (i < j) {
if (a[i] != a[j]) {
f = 1;
break;
}
i++;
j--;
}
if (f == 0) {
cout << "yes!";
} else {
cout << "no!";
}
return 0;
}