My program couldn’t run. How to tell program that the smallest resistance value is series??

Question

#include <stdio.h>
int main(){
int r[5],num,i,parallel_rs=0;
int equiv_resistance;
int min_element;
printf("Enter number of resistances: ");// must be 3 values and above
scanf("%d", &num);
while (1)
{
scanf("%d", &r[i]);
if (r[i] == 0) //Assuming that all values are greater than zero
break; //and input is terminated by a 0 as flag value
if (r[i] < min_element)
min_element = r[i];
i++;
}
if (i < 3)
{
while (i < 3)
{
printf("please enter a value\n"); //keep requesting the values from the user until we get
scanf("%d", &r[i]); //atleast three values
if (r[i] < min_element)
min_element = r[i];
i++;
}
printf("\nEnter value of each resistance:");
for (i=0;i<num;i++){
printf("\nR%d: ",i+1);
scanf("%d",&r[i]);

}
for (i=0;i<num;i++){
parallel_rs+=(1/r[i]);//parallel calc
equiv_resistance += 1 / parallel_rs;//series calc
return equiv_resistance;
printf("\nEquivalent series resistance: %d Ohms", parallel_rs);
}
return 0;
}
}
I am new