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

typedef struct string_t{
    char val[30];
} String;


void insereStrEm(String *result, String *str1, int pos, String *str2){
    int tam1 = strlen(str1->val);
    int tam2 = strlen(str2->val);
    for(int i = 0, k = 0; i < tam1+tam2; i++, k++){
        if(i == pos){
            for(int j = 0; j < tam2; j++){
                result->val[i] = str2->val[j];

                i++;
            }
        }
        result->val[i] = str1->val[k];
    }
}

int main(){
    String str1;
    String str2;
    String result;
    int pos;
    
    fgets(str1.val, 30, stdin);
    fgets(str2.val, 30, stdin);
    scanf("%i", &pos);
    
    int l1 = strlen(str1.val);
    int l2 = strlen(str2.val);
    
    for(int i=0; i<l1; i++){ //remover o \n no final das strings
        if(str1.val[i] == '\n') str1.val[i] = '\0';
        if(str1.val[i] == '\r') str1.val[i] = '\0';
    }
    for(int i=0; i<l2; i++){
        if(str2.val[i] == '\n') str2.val[i] = '\0';
        if(str2.val[i] == '\r') str2.val[i] = '\0';
    }
    
    insereStrEm(&result, &str1, pos, &str2);
    for(int i = 0; i < l1+l2-2; i++){
        printf("%c", result.val[i]);
    }
}