The output of the following C program is_____________.
void f1 ( int a, int b) {
int c;
c = a; a = b;
b = c;
}
void f2 ( int * a, int * b) {
int c;
c = * a; *a = *b; *b = c;
}
int main () {
int a = 4, b = 5, c = 6;
f1 ( a, b);
f2 (&b, &c);
printf ("%d", c - a - b);
}