#include <stdio.h>

int x=10;

int dobro(int x) {
	x = x*2;
	return x;
}

int main(void){
  
	printf("%d\n",x);
	
	int x = 20;
	
	printf("%d\n", x);
	printf("%d\n", dobro(x));
	printf("%d\n", x);
	
	return 0;
}