#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int n;
    cin>>n;
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    if(abs(a-c)%2!=0)
    {cout<<"Impossible";
    return 0;
    }
    else if((abs(a-c)/2)%2!=0 && abs(b-d)%2==0)
    {       cout<<"Impossible";
    return 0;
}
    else if((abs(a-c)/2)%2==0 && abs(b-d)%2!=0)
    {       cout<<"Impossible";
    return 0;
}
    else
    {int k;
     k+=abs(a-c)/2;
     int a=k;
   
     if(abs(b-d)>k)
         k+=((abs(b-d)-k)/2);
         
         
     
        
        
       cout<<k; 
    }
    
   
    return 0;
}