ABC 158

void solve() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N, P;
    string S;
    cin >> N >> P >> S;

    reverse(all(S));

    auto two = [&]() -> ll {
        ll ans = 0;
        rep(i, N) {
            ll x = S[i] - '0';
            if (x % 2 == 0) ans += N - i;
        }
        return ans;
    };

    auto five = [&]() -> ll {
        ll ans = 0;
        rep(i, N) {
            ll x = S[i] - '0';
            if (x % 5 == 0) ans += N - i;
        }
        return ans;
    };

    auto other = [&]() -> ll {
        vll cm(N + 1);
        ll ten = 1;
        rep(i, N) {
            cm[i + 1] = cm[i] + (S[i] - '0') * ten;
            cm[i + 1] %= P;
            ten *= 10;
            ten %= P;
        }

        ll ans = 0;
        fenwick_tree<ll> fw(P);
        rep(i, N + 1) {
            fw.add(cm[i], 1);
        }

        rep(i, P) {
            ll x = fw.sum(i, i + 1);
            ans += x * (x - 1) / 2;
        }
        return ans;
    };

    ll ans = 0;
    if (P == 2)
        ans = two();
    else if (P == 5)
        ans = five();
    else
        ans = other();

    cout << ans << endl;
}