# include <stdio.h>
# include <string.h>
# define MAXN 20
/** elegxos gia tilefoniko arithmo **/

int checkTel(char x[])
{
	int i;
	/**
	 * 10 psifia
	 * Ola na einai arithmoi
	 * Den ksekinaei apo 0
	 */
	if(strlen(x)!=10) return 0;
	if(x[0]=='0') return 0;
	for(i=0;i<strlen(x);i++)
	{
		if(!(x[i]>='0' && x[i]<='9')) return 0;
	}
	return 1;
}

int main()
{
	char x[MAXN];
	printf("Doste ena tilefono gia elegxo ?\n");
	scanf("%s",x);
	if(checkTel(x)) printf("Einai tilefono \n");
	else printf("Den einai tilefono \n");
	return 0;
}