#include <iostream>

int main() {
    int koba_speed, master_speed, cross_num;
    std::cin >> koba_speed >> master_speed >> cross_num;
    int e[cross_num];
    for (int i = 0; i < cross_num; i++) {
        std::cin >> e[i];
    }
    float koba_speed_m_sec = koba_speed * 1000 / 3600;
    float master_speed_m_sec = master_speed * 1000 / 3600;
    for (int i = 0; i < cross_num; i++) {
        double koba_time = e[i] / koba_speed_m_sec;
        if (i + 1 > cross_num - 1) {
            std::cout << "YES" << std::endl;
            return 0;
        }
        if (master_speed_m_sec * koba_time > e[i+1]) {
            std::cout << "NO" << std::endl;
            return 0;
        }
    }
}