#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <math.h>
int main(void)
{
    int kousatennum,kobap,sisyop;
    double kobav,sisyov;
    scanf("%lf %lf",&kobav,&sisyov);
    scanf("%d",&kousatennum);
    int kousaten[101]={0};
    for(int i=0;i<kousatennum;i++)
    {
        scanf("%d",&kousaten[i]);
    }
    kobav/=3600;
    sisyov/=3600;
    for(int i=0;i<kousatennum-1;i++)
    {
        float time=kousaten[i]/kobav;
        kobap=kousaten[i];
        sisyop=sisyov*time;
        if(sisyop>kousaten[i+1])
        {
            printf("NO");
            return 0;
        }
    }
    printf("YES");
}