#include<iostream> using namespace std; int main () { int a,n,m,x; int shang[20],xia[20],zong[20]; cin>>a>>n>>m>>x; shang[1]=a,xia[1]=0,zong[1]=a; int k=0; while(true) { shang[2]=k,xia[2]=k,zong[2]=a; for(int i=3; i<=n-1; i++){ shang[i]=shang[i-1]+shang[i-2]; xia[i]=shang[i-1]; zong[i]=shang[i]-xia[i]+zong[i-1]; } if(zong[n-1]>m) { cout<<"No answer."; return 0; } if(zong[n-1]==m) { cout<<zong[x]; break; } k++; } return 0; }