pku1061青蛙的约会

#include<iostream>
using namespace std;
__int64 result;
__int64 exGCD(__int64 a,__int64 b,__int64 &x,__int64 &y)
{
__int64 t,ret;
if(b==0){ x=1;y=0;return a;}
ret = exGCD(b,a%b,x,y);
t=x; x=y; y=t-(a/b)*y;
return ret;
}
bool fg(__int64 a,__int64 b,__int64 n)
{
__int64 x,y,d,x0;
d=exGCD(a,n,x,y);
if(b%d!=0) return false;
x0=x*(b/d)%n;
result=(x0+n)%n;
return true;
}
int main()
{
__int64 x,y,m,n,L;
while(cin>>x>>y>>m>>n>>L)
{
if(fg(n-m,x-y,L)) cout<<result<<endl;
else cout<<"Impossible"<<endl;
}
return 0;
}