#include <iostream>
#include <stdlib.h>

using namespace std;

int main()
{
    char sir[256];
    int i,j;
    i=0;
    for(j=0;j<26;j++){
        sir[i]='a'+j;
        sir[i+1]='A'+j;
        i+=2;
    }
    sir[i]=NULL;
    for(i=0;sir[i]!=NULL;i++) cout<<sir[i];
    return 0;
}