#include<bits/stdc++.h>
using namespace std;
int sum1[25],sum2[25];
int main(){
	int a,n,m,x;
	cin>>a>>n>>m>>x;
	sum1[2]=1,sum1[3]=2;
	for(int i=4;i<n;i++){
		sum1[i]=sum1[i-1]+sum1[i-2]-1;
		sum2[i]=sum2[i-1]+sum2[i-2]+1;
	}
	int b=(m-a*sum1[n-1])/sum2[n-1];
	cout<<a*sum1[x]+b*sum2[x];
	return 0;
}

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;

long long x,y,m,n,l;

void gcd(long long a,long long b,long long& d,long long & x,long long& y)
{
    if(!b)  {d=a;x=1;y=0;}
    else    {gcd(b,a%b,d,y,x);   y-=x*(a/b);}
}

int main()
{
    cin>>x>>y>>m>>n>>l;
    long long a=((n-m)%l+l)%l;  long long b=l;    long long c=((x-y)%l+l)%l;
    long long d;
    gcd(a,b,d,x,y);
    if(c%d)
        cout<<"Impossible"<<endl;
    else
    {
        long long a1=x*(c/d);
        long long a2=abs(l/d);
        while(a1<0)
            a1+=a2;
        while(a1-a2>=0)
            a1-=a2;
        cout<<a1<<endl;
    }
    return 0;
}