#include <iostream>
using namespace std;
int a,n,m,x;
int A[25] = {0,1,1,2,2},K[25] = {0,0,0,0,1};
int main(){
cin >> a >> n >> m >> x;
if (x <= 2){
cout << a;
return 0;
}
for (int i = 4;i <= n-1;++i){
A[i] = A[i-1] + A[i-2] - 1;
K[i] = K[i-1] + K[i-2] + 1;
}
}
