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

#define MAX_LENGTH 100

int is_valid(char *str){
    for(int i=0;str[i] != '\0';i++){
        if(!isaplha(str[i])){
            return 0;
        }
    }
    return 1;
}
int main(){
    char s1[MAX_LENGTH], s2[MAX_LENGTH];
    
    printf("Enter first string: ";)
    fgets(s1, sizeof(s1), stdin);
    s1[strcspn(s1, "\n")]=0;
    
    printf("Enter second string: ");
    fgets(s2, sizeof(s2), stdin);
    s1[strcspn(s1, "\n")]=0;
    
    if(is_valid(s1) && is_valid(s2)){
        printf("%s%s\n", s1,s2);
    }else{
        printf("Invalid input");
    }
    return 0;
}