#include <fstream>

typedef unsigned long long int Nr;

short ptrn[10]={0,1,4,4,1,1,4,4,2};

inline short simp(Nr k){
    short d=k%10;
    return k%ptrn[d];
}

inline short last(Nr k){
    Nr p=simp(k);
}

int main(){
    Nr n;
    short c=0;
    int t;
    std::ifstream f("cifra.in");
    std::ofstream g("cifra.out");
    f>>n;
    for(Nr i;i<n;i++) c=(c+last(i))%10;
    g<<c;
    g.close();f.close();return 0;
}