#include <vector>
using namespace std;

int main() {
    int n, m;
    double d, a1, an;
    cin >> n >> d >> m >> a1 >> an;
    vector<double> c(n + 1), s(n + 1);
    c[1] = a1; s[1] = 0;
    c[2] = 0;  s[2] = 1;
    for (int i = 2; i < n; i++) {
        c[i + 1] = c[i - 1] - 2 * c[i] + 2 * d;
        s[i + 1] = s[i - 1] - 2 * s[i];
    }
    double a2 = (an - c[n]) / s[n];
    double am = c[m] + s[m] * a2;
    cout << (long long)am << endl;
    return 0;
}