C language pointer issue. Why I am getting 20 instead of 7 as a value of *nn in following code?

pointer_issue.c

#include <stdio.h>

int *ptr(int n);
void nothing(int n1);

int main(void) {
	int *nn = ptr(7);
	nothing(20);
	printf("*nn is %d\n", *nn); // why I am getting 20 instead of 7?
}

int *ptr(int n) {
	int *p = &n;
	printf("p is %d\n", *p);
	return p;
}

void nothing(int n1) {
	// int n2 = n1;
	printf("n1 is %d\n", n1);
}