#include<stdio.h>
main() {

	FILE *g;  /* Arxeio sto opoio exei mpei to encoded keimeno.*/
	int kleidi;
	char c1, c2;
	char os[50];
	printf("\n Eisagogi arxeiou stoxou: ");
	gets(os);
	printf("\n Dose to kleidi kriptografisis: ");
	scanf("%d", &kleidi);
	f=fopen(os, "r+");
	If (!g){
	printf("\n To arxeio den vrethike. \n");
	return;
	}
	while (!feof(g)){
		c2=fgetc(g);
		c1=c2-kleidi;
		if (c1<65) {
			c1+=26;
		}
	fputc(c1, g);
	putchar(c1);
	}
	fclose(g);
}