//#include <bits/stdc++.h> #include <iostream> using namespace std; int main() { //freopen("1519.in", "r", stdin); //freopen("1519.out", "w", stdout); int up[16]; int down[16]; int total[16]; int x, a, n, m; cin >> a >> n >> m >> x; up[1] = a; down[1] = 0; total[1] = a; for (int i = 0; i <= m; i++) { up[2] = i; down[2] = i; total[2] = a; for (int j = 3; j <= n; j++) { up[j] = up[j - 1] + up[j - 2]; down[j] = up[j - 1]; total[j] = total[j - 1] + up[j] - down[j]; } if (total[n - 1] == m) { cout << total[x] << endl; return 0; } } cout << "No answer." << endl; return 0; }