c - How to change a variable in a calling function from a called function?

How should the try() function be modified (and it's call) to get the output as 11 from the program below?

#include 

/* declare try() here */

int main(void)
{
    int x = 10;
    try();              /* Call can change */
    printf("%d\n", x);
    return 0;

}

void try()              /* Signature can change */
{
    /* how to change x here?? */
}