Sean's Encryption Quest!

One day Sean’s friend John wanted him to encrypt a few messages that were to be sent via a TELEGRAM group, so that everyone could see the message, but only those special people who knew decryption can actually understand it. Help Sean write a code that take input values of the type of encryption, a key, and a message to be encrypted that had something to do with the key.

Input Format:
First line containing the type of encryption X.
Second line containing the key K.
Third line containing the message M.

Output Format: The first line contains the encrypted message.

NOTE: The encryption process is based on the simple logic of ADDITION, that is simply adding the value of the key(/modified key) to the characters of the message to be encrypted. ONLY UPPER CASE alphabets need to be considered. X is a number -1 or 0 or 1,
a) -1 denotes the decreasing value of the key,
b) 0 denotes the constant value of the key,
c) 1 denotes the increasing value of the key
d) In case of invalid input value of X simply display “Invalid Input”.

If the input value of K is less than or equal to 0, make the initial value of K as 1

Boundary Conditions: The maximum length of the message M is 200 and it’s minimum length is 1

Example Input/Output 01:
Input:
1
2
SUMMER

Output:
UXQRKY

Explanation: Every time the key is used on a character its value is incremented by 1

Example Input/Output 02:
Input:
-1
6
HOLIDAY

Output:
NTPLFBY

Explanation: Every time the key is used on a character its value is decremented by 1

Example Input/Output 03:
Input:
0
2
ENTERTAINMENT

Output:
GPVGTVCKPOGPV

Example Input/Output 04:
Input:
-1
1
ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

Output: AZYXWVUTSRQPONMLKJIHGFEDCBAZYXWVUTSRQPONMLKJIHGFEDCBAZYXWVUTSRQPONMLKJIHGFEDCBAZYXWVUT

#include<stdio.h>
#include <string.h>
int main()
{
char s[200];
int x,k,i,a=0,c=0;
scanf("%d %d",&x,&k);
scanf("%s",s);
if(k<=0)
    k=1;
if(x==-1)
{
    for(i=0;i<strlen(s);i++)
    {
        if(k<c*-25)
            s[i]=(((s[i]-'A')+k+(c+1)*26)%26)+65;
        else
            s[i]=(((s[i]-'A')+k)%26)+65;
        a++;
        k--;
        if(a==26)
        {
            c++;
            a=0;
        }
    }
    printf("%s",s);
}
else if(x==1)
{
    for(i=0;i<strlen(s);i++)
    {
        s[i]=(((s[i]-'A')+k)%26)+65;
        k++;
    }
    printf("%s",s);
}
else if(x==0)
{
    for(i=0;i<strlen(s);i++)
        s[i]=(((s[i]-'A')+k)%26)+65;
    printf("%s",s);
}
else
    printf("Invalid Input");
}