#include<stdio.h>
#include<string.h>
int main() {
    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 in")
            return 0;
        }
        printf("%c", valve);
    }
    return 0;
}