Ôn thi olympic 2020

int main()
{
	int n;
    FILE *f = fopen("cow4.inp", "r");    // mo file de ghi
 
 	if(f != NULL) {
 		fscanf(f, "%d", &n);
	 	fclose(f);
 	} else {
 		printf("Loi doc file");
 	}

    return 0;
}

#include <stdio.h>
 
int main()
{
    int n = 10;                      // khai bao bien ten
    FILE *f = fopen("output.txt", "w");    // mo file de ghi
 
 	if(f != NULL) {
		fprintf(f, "%3d", n);
	 
	    fclose(f);     // dong file fo
 	} else {
 		printf("Khong doc duoc file!");
	}
 		
    return 0;
}