#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
using namespace std;
typedef long long int lont;
int main() {
	int PA, PB,N;
	int cnt = 0;
	cin >> PA >> PB>>N;
	vector<int>vec(N);
	for (int ia = 0; ia < N; ia++) {
		cin >> vec.at(ia);
	}
	for (int ib = 1; ib < N; ib++) {
		if (vec.at(ib - 1) == vec.at(ib)) {
			cnt++;
		}
	}
	cout << (PA + PB) * cnt << endl;
}