///HEADER FILES///

#include <cstdio>
#include <cstring>
#include <cmath>
#include <cctype>
#include <stack>
#include <queue>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <cstdlib>
#include <complex>
#include <iomanip>
#include <utility>
#include <bitset>
#include <list>
#include <assert.h>
#include <numeric>
#include <fstream>
using namespace std;

///DEFINES///

///ALWAYS USEFUL
#define     caseprint(case)     printf("Case %d: ", case ++)
#define     caseprintnl(case)   printf("Case %d:\n", case ++)
#define     clr(a)              memset(a, 0, sizeof(a))
#define     mem(a, b)           memset(a, b, sizeof(a))
#define     pb                  push_back
#define     pp                  pop_back
#define     full(v)             v.begin(), v.end()
#define     sort_vec(v)         sort(full(v))
#define     sf                  scanf
#define     pf                  printf
#define     NL                  pf("\n")
#define     sz(a)               (int)a.size()
#define     bitcheck(n, pos)    (n & (1<<(pos)))
#define     biton(n, pos)       (n  (1<<(pos)))
#define     bitoff(n, pos)      (n & ~(1<<(pos)))
#define     sqr(a)              ((a)*(a))

///SCAN
#define     sfs(a)              scanf("%s", &a)
#define     sfi1(a)             scanf("%d", &a)
#define     sfi2(a, b)          scanf("%d %d", &a, &b)
#define     sfi3(a, b, c)       scanf("%d %d %d", &a, &b, &c)
#define     sfi4(a, b, c, d)    scanf("%d %d %d %d", &a, &b, &c, &d)
#define     sfd1(a)             scanf("%lf", &a)
#define     sfd2(a, b)          scanf("%lf %lf", &a, &b)
#define     sfd3(a, b, c)       scanf("%lf %lf %lf", &a, &b, &c)
#define     sfd4(a, b, c, d)    scanf("%lf %lf %lf %lf", &a, &b, &c, &d)
#define     sfll1(a)            scanf("%lld", &a)
#define     sfll2(a, b)         scanf("%lld %lld", &a, &b)
#define     sfll3(a, b, c)      scanf("%lld %lld %lld", &a, &b, &c)
#define     sfll4(a, b, c, d)   scanf("%lld %lld %lld %lld", &a, &b, &c, &d)
#define     sfull1(a)           scanf("%llu", &a)
#define     sfull2(a, b)        scanf("%llu %llu", &a, &b)
#define     sfull3(a, b, c)     scanf("%llu %llu %llu", &a, &b, &c)
#define     sfull4(a, b, c, d)  scanf("%llu %llu %llu %llu", &a, &b, &c, &d)

///GEOMETRY
#define     ang(a, b, c)            acos((sqr(b)+sqr(c)-sqr(a))/(2.0*b*c))
#define     dist(x1, y1, x2, y2)    sqrt(sqr(x1-x2)+sqr(y1-y2))

///TYPES///
typedef     long long ll;
typedef     unsigned long long ull;
typedef     pair<int, int>      pii;
typedef     pair<ll, ll>        pll;

struct debugger
{
    template<typename T> debugger& operator, (const T& v)
    {
        cerr<<v<<" ";
        return *this;
    }
} dbg;
#define deb(args ...){dbg, args; cerr<<endl;}

//ll extGcd(ll a, ll b, ll& x, ll& y){if (b == 0){x = 1;y = 0;return a;}else{int g = extGcd(b, a % b, y, x);y -= a / b * x;return g;}}
//ll modInv(ll a, ll m){ll x, y; extGcd(a, m, x, y); x %= m; while (x < 0){x += m;} return x;}
//ll BigMod(ll b, ll p, ll m) {if(!p) return 1; ll x=BigMod(b,p/2,m); x=(x*x)%m; if(p&1) x=(x*b)%m; return x;}
//ll bigmod(ll B,ll P,ll M){ ll R=1%M; while(P>0) {if(P%2==1){R=(R*B)%M;}P/=2;B=(B*B)%M;} ret urn R;} /// (B^P)%M

//int x[] = {0,0,-1,1};//4-ways
//int y[] = {1,-1,0,0};//4-ways
//int x[] = {-1,-1,-1,0,0,1,1,1};//8-ways
//int y[] = {-1,0,1,-1,1,-1,0,1};//8-ways
//int x[] = {-2,-2,2,2,1,1,-1,-1};//knight moves
//int y[] = {1,-1,1,-1,2,-2,2,-2};//knight moves

///CONSTANTS
#define     pi                  acos(-1.0)
#define     ex                  exp(1)

///OTHERS
#define     READ                freopen("input.txt","r",stdin);
#define     WRITE               freopen("out.txt","w",stdout);
#define     accelerate          ios_base::sync_with_stdio(false); cin.tie(NULL)
#define     debug               printf("Ok\n")
#define     MOD                 1000000007
#define     M                   500000

int main()
{
    accelerate;

    ll n;

    while(cin>>n)
    {
        string ans = "";

        while(n)
        {
            n--;
            ll now = n%26;
            ans += now + 'a';
            n /= 26;
        }

        reverse(full(ans));

        cout<<ans<<endl;
    }

    return 0;
}



Measured memory_bytes: 3672