#include<stdio.h>
#include<math.h>


#define N 81

int main(void){
    int x = 0;
    int y = 0;
    int n = 0;
    int a[N];
    int flag[10];
    int i = 0;

    while(flag[0]==0){
        printf("Please, input X\n");
        scanf("%d", &x);
        if(1 < x && x <= 99){
            flag[0] = 1;
        }
    }
    while(flag[1]==0){
        printf("Please, input Y\n");
        scanf("%d", &y);
        if(x < y && y <= (int)pow(10.0,2.0)){
            flag[1] = 1;
        }
    }    
    while(flag[2]==0){
        printf("Please, input N\n");
        scanf("%d", &n);
        if(1 <= n && n <= N){
            flag[2] = 1;
        }
    }
    for(i = 1; i <= n; i++){
        while(flag[3]==0){
            printf("Please, input A%d\n", i);
            scanf("%d", &a[i]);
            if(0 < a[i] && a[i] <= (int)pow(10.0,5.0)){
                if(a[i-1] < a[i]){
                    flag[3] = 1;
                }
            }
        }
        flag[3] = 0;
    }
    for(i = 1; i <= n-1; i++){
        if(((1.0/(double)x)*a[i]-(1.0/(double)y)*a[i])*y+a[i] > a[i+1]){
            printf("No\n");
            return 0;
        }
    }
    printf("Yes\n");


    return 0;
}