0

# include<iostream>
# include<cmath>   
# include<cstdio>
# include<cmath>     //平方根
# include<cstdlib>     //随机数
# include<ctime>
using namespace std;
int main(){
   int n,a[4],i;
   cin>>n;
   for (i=1;i<=4;i++){
       cin>>a[i];
   }
   if (a[2]-a[1]!=a[3]-a[2]){
       cout<<a[1]*pow(a[2]/a[1]*1.0,n-1);
   }
   else{
       cout<<a[1]+(a[2]-a[1])*(n-1);
   }
   return 0;
}