Book writing

#include <iostream>

using namespace std;
typedef long long ll;

ll pot(ll k, ll e, ll m) {
	if (e == 0) return 1%m;
	if (e == 1) return k%m;
	if (e%2 == 0) {
		ll h = pot(k, e/2, m);
		return (h*h)%m;
	}
	return (k*pot(k, e-1, m))%m;
}

int main() {
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	ll n, m;
	cin >> n >> m;
	cout << pot(3, n-1, m) << "\n";
	return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED