#include <stdio.h.
#include <string.h>
int amin()
{
    char str[100];
    scanf("%s",str);
    int len=strlen(str);
    for (int i =0;i<len;i+=2)
    {
        int value1=str[i]-'0';
        int value2=str[i+1]-'0';
        int value=value1*10+value2;
        if(value<65 || value>122 || value ==96)
        {
            printf("Invalid Input");
            return 0;
        }
        printf("%c",value);
    }
    return 0;
}