#include<stdio.h>

int main() {
int h1, h2,hnum,i,oo=0,son;
int h[1000];

	scanf("%d", &h1);
	scanf("%d", &h2);
	scanf("%d", &hnum);

	for (i = 0; i < hnum; i++) {
		scanf("%d",& h[i]);
	}
	for (i = 1; i < hnum; i++) {
		if (h[i] == h[i - 1]) {
			oo++;
		}
	}
	son = oo*(h1 + h2);
	

	printf("%d\n", son);
	
	return 0;
}