i need to build a basic program that print the num pi....

output: 3.0000000000

what is wrong??

Code:# include <stdio.h> double long exp1(double base, unsigned long exp) { double sum=1; unsigned long i; for (i=0; i<exp; i++) { sum=sum*base; } return sum; } double long pi(int k) { double long sum=0; if (k==0) { sum=(47/15); return sum; } sum=((1/(exp1(16,k)))*((4/((8*k)+1))-(2/((8*k)+4))-(1/((8*k)+5))-(1/((8*k)+6)))) + pi(k-1); return sum; } int main() { int k=0; printf("please enter how many k of pi do you like\n"); scanf_s("%d",&k); if (k<0) { while (k<0) { printf("please enter positive number\n"); scanf_s("%d",&k); } } printf("the number is %.10lf\n",pi(k)); return 0; }