#include <stdio.h>
#include <string.h>

int main()
{
	int k;
	char ar0[20];
	char ar1[20];
	printf("Enter your key: ");
	scanf("%d", &k);
	k=(k%26);
	printf("Enter ciphertext.\n");
	scanf("%s", &ar0[0]);
	int n=strlen(ar0);
	for(int i=0; i<n; i++)
	{
		if(ar0[i]-k<=90 && ar0[i]-k>=65)
			ar1[i]=ar0[i]-k;

		else
			ar1[i]=ar0[i]-k+26;
	}

	printf("Deciphering.... \n");
    printf("%s \n", &ar1[0]);
}