Palindromi

#include <bits/stdc++.h>
using namespace std;
 
//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")

#define debug(x) cout << (x) << "\n"
#define ll long long
#define ar array
#define pb push_back
#define pf push_front
#define fi first
#define se second

string s;

void solve() {
	cin >> s;
	int n=s.size(), ans=0;
	for(int i=0; i<n/2; i++) {
		if(s[i]!=s[n-i-1]) {
			ans++;
		}
	}
	cout << ans << "\n";
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
	int T=1;
    //cin >> T;
	while(T--)
		solve();
    return 0;
}

Test 1 (public)

Verdict: ACCEPTED

Test 2 (public)

Verdict: ACCEPTED

Test 3 (public)

Verdict: ACCEPTED

Test 4 (public)

Verdict: ACCEPTED

Test 5 (public)

Verdict: ACCEPTED

Test 6 (public)

Verdict: ACCEPTED

Test 7 (public)

Verdict: ACCEPTED

Test 8 (public)

Verdict: ACCEPTED

Test 9 (public)

Verdict: ACCEPTED

Test 10 (public)

Verdict: ACCEPTED