#include <stdio.h>

//  int y = 0; //what happens if we uncomment this line?

int* f(int x) {
  int *p;
  if(x) {
    int y = 3;
    p = &y; 
  }
  y = 4;
  *p = 7; 
  return p; 
}

void g(int *p){
  *p = 123; 
}

void h() {
  //  int y = 0; //what happens if we uncomment this line?
  g(f(7)); 
}

int main(){
  h();
}