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#pragma comment(linker, "/STACK:268435456")
#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <deque>
#include <queue>
#include <list>
#include <cstring>
#include <complex>
#include <ctime>
#include <bitset>
#include <iomanip>
#include <sstream>
using namespace std;
const double PI = 3.1415926535897932384626433832795;
template<class T> T min(T &a, T &b) { return (a<b) ? a : b; }
template<class T> T max(T &a, T &b) { return (a>b) ? a : b; }
template<class T> T sqr(T &a) { return a*a; }
template<class T> T abs(T &a) { return (a<0) ? (-a) : a; }
typedef long long ll;
typedef long long LL;
typedef pair<int,int> ii;
#define all(v) (v).begin(),(v).end()
#define sz(v) ((int)((v).size()))
#define PB push_back
#define MP make_pair
#define CLR(a) memset((a),0,sizeof(a))
#define fori(i,n) for(int i=0;i<(n);i++)
//------------------------------------------------------------------------------

int main()
{
#ifdef _MSC_VER
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
#endif
        int k;
        cin >> k;
        string s;
        cin >> s;
        fori(i,sz(s))
        {
                cout << char('A'+(((s[i]-'A'-3*(i+1)-k)%26+26)%26));
        }
}