Palindromi

#include <bits/stdc++.h>

#define F0R(n) for (int i=0; i<n; i++)
#define FOR(from, to) for (int i = from; i < to; i++)
#define R0F(n) for (int i = n; i>=0; --i)
#define ROF(from, to) for (int i = from; i >= to; --i)

#define ll long long
#define mod (int) (1e9 + 7)
#define vi vector<int>
#define vll vector<ll>
#define vc vector<char>
#define pii pair<int, int>
#define pci pair<char, int>
#define pll pair<ll, ll>
#define YES cout << "YES\n";
#define NO cout << "NO\n";
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using namespace std;

void soln() {
    string s;
    cin >> s;
    int N = s.length(), ans = 0;
    int n = N/2;

    for (int i=0; i<n; ++i) {
        if (s[i] != s[N-1-i]) ++ans;
    }
    cout << ans;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int tc=1;
    //cin >> tc;
    while (tc--) soln();
    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