#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	int n, a, b;
	cin >> n >> a >> b;
	vector<int> k(n + 1);
	rep(i, 0, n + 1) cin >> k[i];
	double dx = 0.0001, s = 0;
	for(double x = a; x < b; x += dx) {
		rep(j, 0, n + 1) s += pow(x, j) * k[j];
	}
	ll ans = s * dx;
	cout << ans << endl;
}