#include <stdio.h>
 
int main() {
    FILE *file1, *file2, *file3;
    char filename1[100], filename2[100], filename3[100];
    char ch;
 
    // Step 1: Get filenames from user
    printf("Enter name of first file: ");
    scanf("%s", filename1);
 
    printf("Enter name of second file: ");
    scanf("%s", filename2);
 
    printf("Enter name of output file: ");
    scanf("%s", filename3);
 
    // Step 2: Open first two files in read mode
    file1 = fopen(filename1, "r");
    file2 = fopen(filename2, "r");
 
    // Step 3: Open third file in write mode
    file3 = fopen(filename3, "w");
 
    // Step 4: Validate file opening
    if (file1 == NULL || file2 == NULL || file3 == NULL) {
        printf("Error opening files. Please check filenames.\n");
        return 1;
    }
 
    // Step 5: Copy contents of first file into output file
    while ((ch = fgetc(file1)) != EOF)
        fputc(ch, file3);
 
    // Step 6: Copy contents of second file into output file
    while ((ch = fgetc(file2)) != EOF)
        fputc(ch, file3);
 
    // Step 7: Close all files
    fclose(file1);
    fclose(file2);
    fclose(file3);
 
    printf("\nFiles '%s' and '%s' merged into '%s' successfully.\n", filename1, filename2, filename3);
 
    return 0;
}