Prase

#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define F first
#define S second
using pi=pair<int,int>;
using ii=long long;
int main()
{
    map<string, int> m;
    int n;
    cin >> n;
    int r = 0;
    for (int i = 0; i < n; ++i) {
        string s;
        cin >> s;
        if (m[s] > i- m[s]) {
            r++;
        }
        m[s]++;
    }
    cout << r << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED