/*
#include <stdio.h>
int main()
{
int a;
scanf("%d",&a);
if(a%10!=0)
{
printf("-1");
return 0;
}
if(1<=a/300)
{
printf("%d ",a/300);
a=a-(a/300)*300;
}
else
{
printf("0 ");
}
if(1<=a/60)
{
printf("%d ",a/60);
a=a-(a/60)*60;
}
else
{
printf("0 ");
}
if(1<=a/10)
{
printf("%d ",a/10);
}
else
{
printf("0");
}
return 0;
}
*/
#include <stdio.h>
int main()
{
int a,i,b='A',c='A',j;
scanf("%d",&a);
while()
{
if(a>26)
{
b++;
c='A';
a=a-26;
}
else
{
c=c+a-1;
break;
}
}
printf("%c%c",b,c);
return 0;
}
/*
A 1
Z 26
AA 27 = 26+1
AZ 52= 26+26
BA 52+1
BZ 52+26
CA 52+26+1
CZ
ZZ = 26*26
AAA => 26*26 +1
*/