#include <iostream>

using namespace std;
typedef pair<int,pair<int,int>> piii;
typedef long long ll;
piii dp[70][10][10][10];
int main(){
    ll i,j,l,m,p,q,r,k; cin >> p >> q >> r >> k;
    p %= 10; q %= 10; r %= 10;
    for(i=0;i<10;i++){
        for(j=0;j<10;j++){
            for(l=0;l<10;l++) dp[0][i][j][l] = {(i + j + l)%10,{i,j}};
        }
    }
    for(i=1;i<=60;i++){
        for(j=0;j<10;j++){
            for(l=0;l<10;l++){
                for(m=0;m<10;m++){
                    piii w = dp[i - 1][j][l][m];
                    int x = w.first,y = w.second.first,z = w.second.second;
                    dp[i][j][l][m] = dp[i - 1][x][y][z];
                }
            }
        }
    }
    k -= 3;
    for(i=60;i>=0;i--){
        if(k>=(1LL<<i)){
            //cout << i << endl;
            piii w = dp[i][r][q][p];
            r = w.first,q = w.second.first,p = w.second.second; 
            //cout << r << " " << q << " " << p << endl;
            k -= (1LL<<i);
        }
    }
    cout << r << endl;
}