#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>

#define log2 60
#define pi64 "%" PRId64
#define si64 "%" SCNd64

int dub[log2 + 1][10][10][10][3];

int main() {
    int64_t p, q, r, k;
    scanf(si64 si64 si64 si64, &p, &q, &r, &k);
    p %= 10; q %= 10; r %= 10;

    for (int i = 0; i < 10; ++i) {
        for (int j = 0; j < 10; ++j) {
            for (int k = 0; k < 10; ++k) {
                dub[0][i][j][k][0] = j;
                dub[0][i][j][k][1] = k;
                dub[0][i][j][k][2] = (i + j + k) % 10;
            }
        }
    }

    for (int l = 1; l <= log2; ++l) {
        for (int i = 0; i < 10; ++i) {
            for (int j = 0; j < 10; ++j) {
                for (int k = 0; k < 10; ++k) {
                    dub[l][i][j][k][0] =
                        dub[l - 1][dub[l - 1][i][j][k][0]][dub[l - 1][i][j][k][1]][dub[l - 1][i][j][k][2]][0];
                    dub[l][i][j][k][1] =
                        dub[l - 1][dub[l - 1][i][j][k][0]][dub[l - 1][i][j][k][1]][dub[l - 1][i][j][k][2]][1];
                    dub[l][i][j][k][2] =
                        dub[l - 1][dub[l - 1][i][j][k][0]][dub[l - 1][i][j][k][1]][dub[l - 1][i][j][k][2]][2];
                }
            }
        }
    }

    if (k == 1) {
        printf(pi64 "\n", p);
        return 0;
    }

    if (k == 2) {
        printf(pi64 "\n", q);
        return 0;
    }

    if (k == 3) {
        printf(pi64 "\n", r);
        return 0;
    }

    k -= 3;
    for (int i = 0; (k >> i) != 0; ++i) {
        if (!(k & (INT64_C(1) << i))) {
            continue;
        }

        int a = dub[i][p][q][r][0];
        int b = dub[i][p][q][r][1];
        int c = dub[i][p][q][r][2];
        p = a; q = b; r = c;
    }

    printf(pi64 "\n", r);
}