#include<iostream> #include<cmath> #include<cstdio> #include<cstring> using namespace std; int main() //主函数入口 { int i = 0,j,num = 0,a,n,m,x; int up[16] = {0},down[16] = {0},arr[16] = {0}; cin >> a >> n >> m >> x; arr[1] = arr[2] = a; up[1] = a; down[1] = 0; for(j = 0; j < m;j++) { up[2] = j; down[2] = j; for(i = 3;i < n;i++) { up[i] = up[i-1] + up[i-2]; down[i] = up[i-1]; arr[i] = arr[i-1] + up[i] - down[i]; } if(arr[n-1] == m) { cout << arr[x] <<endl; return 0; } } cout << "No answer."<<endl; return 0; //结束整个程序 }