سلسلة#include <bits/stdc++.h>

#include <bits/stdc++.h> using namespace std; int main (){ double k, r, s, y, x; cin>>x>>k>>r>>s; if(cos(x)==cos(r*s)) y=x*x*exp(2*k)+log(abs(r*x)); else if(cos(x)>(cos(r*s)) y=pow(x*x,1./3)+ sqrt(abs(k+r*s*x)); else y=atan(k*x+r*s); cout<<y; }