#include <stdio.h>

#include <string.h>

void encrypt(char *message, int shift) {

    int len = strlen(message);

    for (int i = 0; i < len; i++) {

        if (message[i] >= 'A' && message[i] <= 'Z') {

            message[i] = (message[i] - 'A' + shift) % 26 + 'A';

        } else if (message[i] >= 'a' && message[i] <= 'z') {

            message[i] = (message[i] - 'a' + shift) % 26 + 'a';

        }

    }

}

void decrypt(char *message, int shift) {

    int len = strlen(message);

    for (int i = 0; i < len; i++) {

        if (message[i] >= 'A' && message[i] <= 'Z') {

            message[i] = (message[i] - 'A' - shift + 26) % 26 + 'A';

        } else if (message[i] >= 'a' && message[i] <= 'z') {

            message[i] = (message[i] - 'a' - shift + 26) % 26 + 'a';

        }

    }

}

int main() {

    char message[100];

    int shift;

    printf("Enter a message: ");

    fgets(message, sizeof(message), stdin);

    printf("Enter the shift value: ");

    scanf("%d", &shift);

    // Remove newline from the message

    message[strcspn(message, "\n")] = 0;

    // Encrypt and print

    encrypt(message, shift);

    printf("Encrypted message: %s\n", message);

    // Decrypt and print

    decrypt(message, shift);

    printf("Decrypted message: %s\n", message);

    return 0;

}