I was looking at errichito’s blog and noticed he wasn’t lgm and looked at his blog and his recent contest. He recently participated in the spectral cup and dropped over a hundred points. I looked at his position and saw many around him who were much lower rated than him but one stood out, prantamohajn.

This person is currently roughly 1100 rated and this was his second contest beating a former lgm no less. Not entirely something that is incriminating but certainly suspicious to perform at a very high level in second contest. Potentially further incriminating would be just 4 days prior this person put up a result of getting around 3000th in a div 2. This is a pretty absurd improvement and i believe that this mostly rules out the statement this person is simply a former experienced person who moved to codeforces.

Here is some of their code in the recent contest,

include

using namespace std;

typedef unsigned long long ull;

void solve() { int n; if (!(cin >> n)) return;

ull total_mask = 0;
for (int i = 0; i < n; i++) total_mask |= (1ULL << i);

// Initial element choice
cout << 0 << endl;

// First query to distinguish k=1 from k=2,3
cout << "I 0" << endl;
int size_s;
if (!(cin >> size_s)) exit(0);
if (size_s == -1) exit(0);

if (size_s == 1) {
    cout << "I " << total_mask << endl;
    if (!(cin >> size_s)) exit(0);
    if (size_s == -1) exit(0);

    // Binary search for c in the set S = {0, c}.
    ull low = 1, high = total_mask;
    while (low < high) {
        ull mid = low + (high - low + 1) / 2;
        cout << "Q " << mid << endl;
        int res;
        if (!(cin >> res)) exit(0);
        if (res == -1) exit(0);
        if (res >= 1) low = mid; // c is in S and c >= mid
        else high = mid - 1;
    }
    cout << "A 1 " << low << endl;
} else {
    // Case k=2 or 3: f(0)=c, so S = {0, c}.
    // Binary search for c in the set S = {0, c}.
    ull low = 1, high = total_mask;
    while (low < high) {
        ull mid = low + (high - low + 1) / 2;
        cout << "Q " << mid << endl;
        int res;
        if (!(cin >> res)) exit(0);
        if (res == -1) exit(0);
        if (res >= 1) low = mid;
        else high = mid - 1;
    }
    ull c = low;

    if (c == total_mask) {
        // Distinguish k=2 and k=3 by inserting f(1).
        cout << "I 1" << endl;
        if (!(cin >> size_s)) exit(0);
        if (size_s == -1) exit(0);
        // If k=2, f(1) = 1 | total_mask = total_mask, size remains 2.
        // If k=3, f(1) = 1 ^ total_mask = total_mask - 1, size becomes 3.
        if (size_s == 2) {
            cout << "A 2 " << c << endl;
        } else {
            cout << "A 3 " << c << endl;
        }
    } else {
        // Distinguish k=2 and k=3 by inserting f(total_mask).
        cout << "I " << total_mask << endl;
        if (!(cin >> size_s)) exit(0);
        if (size_s == -1) exit(0);

        // Check if total_mask was added to the set.
        cout << "Q " << total_mask << endl;
        int res;
        if (!(cin >> res)) exit(0);
        if (res == -1) exit(0);
        // If k=2, total_mask | c = total_mask.
        // If k=3, total_mask ^ c = ~c < total_mask (as c >= 1).
        if (res >= 1) {
            cout << "A 2 " << c << endl;
        } else {
            cout << "A 3 " << c << endl;
        }
    }
}

}

int main() { // Basic setup for I/O efficiency. ios_base::sync_with_stdio(false); cin.tie(NULL);

int t;
if (!(cin >> t)) return 0;
while (t--) {
    solve();
}
return 0;

}

While a definite verdict cannot be made, I feel the likely occurrence is obvious yet again, these are simply observations and not a formal accusation.