#include<stdio.h>
#include<string.h>
#include<ctype.h>
int main() {
    char s[11];
    fgets(s, 11, stdin);
    s[strcspn(s, "\n")] = 0;
    int len = strlen(s);
    if (len == 0 || len > 10) {
        printf("Invalid Input\n");
        return 0;
    }
    for (int i = 0; i < len; i++) {
        if (!isalpha(s[i]) && s[i] != ''){
            printf("Invalid Input\n");
            return 0;
        }
        for (int j = 0; j <= i; j++){
            printf("%c",s[j]);
        }
        printf("\n")
    }
    return 0;
}