int travelAroundTheWorld(long N, const vector<long>& A, const vector<long>& B, long capacity) {
    int answer = 0;
    vector<long> cache(2 * N);
    for (int i = 2 * N - 2; i >= 0; i--) {
        if (capacity < cache[i + 1] + B[i % N]) break;
        if (A[i % N] >= capacity) cache[i] = 0;
        else cache[i] = max(cache[i + 1] + B[i % N] - A[i % N], 0L);
        if (i < N and cache[i] == 0) answer++;
    }
    return answer;
}