/*
--------------              |   /
      |                     |  /
      |                     | /
      |             *       |/          |    |         ------            *
      |                     |           |    |        /      \
      |             |       |\          |    |       |       |\          |
   \  |             |       | \         |    |       |       | \         |
    \ |             |       |  \        |    |        \     /   \        |
     V              |       |   \        \__/|         -----     \       |
*/
#include <bits/stdc++.h>
using namespace std;
#define debug(x) cerr << "\e[1;31m" << #x << " = " << (x) << "\e[0m\n"
#define print(x) emilia_mata_tenshi(#x, begin(x), end(x))
template<typename T> void emilia_mata_tenshi(const char *s, T l, T r) {
	cerr << "\e[1;33m" << s << " = [";
	while(l != r) {
		cerr << *l;
		cerr << (++l == r ? ']' : ',');
	}
	cerr << "\e[0m\n";
}

#define EmiliaMyWife ios::sync_with_stdio(0); cin.tie(NULL);
using ll = int64_t;
using ull = uint64_t;
using ld = long double;
using uint = uint32_t;
const double EPS  = 1e-8;
const int INF     = 0x3F3F3F3F;
const ll LINF     = 4611686018427387903;
const int MOD     = 1e9+7;
/*--------------------------------------------------------------------------------------*/

tuple<int, int, int> nxt[60][10][10][10];
signed main() { EmiliaMyWife
	for(int i = 0; i < 10; i++)
		for(int j = 0; j < 10; j++)
			for(int k = 0; k < 10; k++) {
				int x = (i + j + k) % 10;
				nxt[0][i][j][k] = {j, k, x};
			}
	for(int n = 1; n < 60; n++)
		for(int i = 0; i < 10; i++)
			for(int j = 0; j < 10; j++)
				for(int k = 0; k < 10; k++) {
					auto [a, b, c] = nxt[n - 1][i][j][k];
					nxt[n][i][j][k] = nxt[n - 1][a][b][c];
				}
	int p, q, r;
	ll k;
	cin >> p >> q >> r >> k;
	k--;
	p %= 10, q %= 10, r %= 10;
	for(int i = 0; i < 60; i++)
		if(k >> i & 1) {
			auto [a, b, c] = nxt[i][p][q][r];
			p = a;
			q = b;
			r = c;
		}
	cout << p << '\n';
}