#include<stdio.h>
#include<ctype.h>
#include<string.h>
int isAlphaAscii(int num)
{
    return (num >= 65 && num <=90)|| (num >= 97 && num <= 122);
}
int main()
{
    char input[110];
    if(fgets(input,  sizeof(input),stdin)!= NULL)
    {
        input[strcspn(input," ")]= 0;
        int len = strlen(input);
        if(len%2 !=0)
        {
            printf("Inalid Input");
            return 0;
        }
        for(int i = 0;i<len;++i)
        {
            if(!isdigit(input[i]))
            {
                printf("Invalid Input");
                return 0;
            }
        }
        char output[60];
        int outIdx = 0;
        for(int i = 0;i<len;i+= 2)
        {
            int val = (input[i] - '0')* 10 + (input[i+1] - '0');
            if(!isAlphaAscii(val))
            {
                printf("Invalid Input");
                return 0;
            }
            output[outIdx++] = (char)val;
        }
        output[outIdx]= ' ';
        printf("%s",output);
    }
    else
    {
        printf("Invalid Input");
    }
}
return 0;
}