#include <iostream>

 #include <cstdio>

 #include <cstring>

 #include <cstdlib>

 #include <string>

 #include <vector>

 #include <map>

 #include <set>

 #include <queue>

 #include <sstream>

 #include <algorithm>

 using namespace std;

 #define pb push_back

 #define mp make_pair

 #define ms(a, b)  memset((a), (b), sizeof(a))

 #define eps 0.0000001

 typedef long long LL;

 const int INF = 2e9;

 const LL LNF = 9e18;

 const int mod = 1e9+;

 const int maxn = ***;

 int a[maxn+];

 int vis[][][][];

 void solve()

 {

     a[] = a[] = a[] = ;

     for(int i = ; i<maxn+; i++)

     {

         for(int j = ; j>=; j--)

         {

             if(vis[a[i-]][a[i-]][a[i-]][j]==)

             {

                 vis[a[i-]][a[i-]][a[i-]][j] = ;

                 a[i] = j;

                 break;

             }

         }

     }

 }

 int main()

 {

     int n;

     solve();

     while(scanf("%d",&n)!=EOF)

     {

         if(n>maxn+)

             printf("Impossible");

         else

             for(int i = ; i<n; i++)

                 printf("%c",a[i]+'a');

         putchar('\n');

     }

 }