5678

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

int main()
{

    while( 10 < 20 ) {
        char in[50];
        char out[50];
        printf("Enter the input file name: ");
        scanf("%[^\n]%*c", in);
        printf("Enter the output file name: ");
        scanf("%[^\n]%*c", out);
        int value = strcmp(in,out);
        if ( value == 0){
            printf("Cannot use the same file name. Please re-enter.\n\n");
        }
        else{
            printf("Excellent!");
            break;
        }
    }

    return 0;
}