// vigenere encryption
//
#include<stdio.h>
//#include<cs50.h>
#include<ctype.h>
#include<stdlib.h>
#include<string.h>

int main(int argc,char *argv[]){
char *ptext;   // for plaintext
int n;
int j=0;
int moves=0;

// if key was not passed
    if(argc!=2){
        printf("improper no of arguments passed\n");
        exit(1);
    }
// for wrong format error of key
    n=strlen(argv[1]);
    for(int i=0;i<n;i++){
        if(!isalpha(argv[1][i])){
			printf("wrong format of argument\n");
            exit(1);
        }
    }


// converting Plain-text to cypher
    char *key;
    key=argv[1];

    //getting the plaintext
    //ptext=GetString();
    scanf("%[^\n]s",ptext);
    int plen=strlen(ptext);
    //printf("key = %s   %d = plen",key,plen);
    char ctext[plen];


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

        if(j==n)
    		j=0;

    // key evaluation

	// for only encrypting alphabetical characters
        if(isalpha(ptext[i])){
            //modifing key value
    		if(islower(key[j]))
    		   moves = ( key[j] - 'a' );
    		else
    		   moves = ( key[j] - 'A' );

    	    //for lower case alhabets
    		if (islower(ptext[i]))
    		{
    		    //overflow
                if(ptext[i]+moves  > 'z'){
    				moves=(ptext[i]+moves)-'z';
    				ctext[i] = ('a'+ moves-1);
    				j++;
    			}
    			else{
    			    ctext[i] = (ptext[i]+ moves);
    			    j++;
    				}
    		}
            //for upper case alphabets
    		else if (isupper(ptext[i]))
    		{
    	        if(ptext[i]+moves  > 'Z'){
    			    moves=(ptext[i]+moves)-'Z';
    				ctext[i]=('A'+moves-1);
    				j++;
    		     }
    			 else{
			         ctext[i] = (ptext[i]+ moves);
    			     j++;
				    }
			 }
    	}
    	else{
    			ctext[i]=ptext[i];
    		 }
    }

    // printing cypher
    printf("%s",ctext);
	// ctext printing extra text on 'a' as key and 'a' as plaintext

    return 0;
}