#include<fstream.h>
ifstream f("cifra.in");
ofstream g("cifra.out");
long n,s,us,i,uc,r;
int main()
{f>>n;
s=0;
for(i=1;i<=n;i++)
{uc=i%10;
if(uc==0 || uc==1 || uc==5 ||uc==6)
s=s+uc;
else
if(uc==2)
{r=i%4;
if(r==0)
s=s+6;
else
if(r==1)
s=s+2;
else
if(r==2)
s=s+4;
else
if(r==3)
s=s+8;}
else
if(uc==3)
{r=i%4;
if(r==0)
s=s+1;
else
if(r==1)
s=s+3;
else
if(r==2)
s=s+9;
else
if(r==3)
s=s+7;}
else
if(uc==4)
{r=i%2;
if(r==0)
s=s+6;
else
if(r==1)
s=s+4;}
else
if(uc==7)
{r=i%4;
if(r==0)
s=s+1;
else
if(r==1)
s=s+7;
else
if(r==2)
s=s+9;
else
if(r==3)
s=s+3;}
else
if(uc==8)
{r=i%4;
if(r==0)
s=s+6;
else
if(r==1)
s=s+8;
else
if(r==2)
s=s+4;
else
if(r==3)
s=s+2;}
else
if(uc==9)
{r=r%2;
if(r==0)
s=s+1;
else
if(r==1)
s=s+9;}}
g<<s%10;
f.close();
g.close();
return 0;}