Help with C?

I'm writing a program for class that approximates the exponential function, e^x.

Yes, I know its already built in, but I'm supposed to do it manually to show I know how. Problem is, something doesn't work quite right and after 12 iterations, it blows up. What should happen is that each new summed value should be smaller and smaller to the point I hone in on a final value.

Anyway, can anyone provide some help? This is what I have:

Code:

#include <stdio.h>
#include <math.h>

//factorial function prototype
int factorial (int);


//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
main ()
{

//Declaration of variables and setting of initial values
int n,i;
double y,ex,ugh,z;


//take input from user for x and n
printf("Please enter a value for the number of terms (n) and value to be approximated (x)  > ");
scanf("%d%lf", &n, &y);

//assign variable values
ex=0;
ugh=y;
z=y;


//for-loop to do e^x approximation
for (i=0; i<=n; i=i+1)
        {
		 ex=ex+(pow(y,i)/factorial(i)); 
        }




//actual exp function		
y=exp(ugh);

//output
printf("The value of exp(%g) is %g \n\n", z,y);
printf("The approximate  value of %d terms is %g \n\n",  n+1,ex);
}


//factorial function
int factorial(int n)
 {
  if (n<=1)
	return(1);
  else
	n=n*factorial(n-1);
	return(n);
}

 

Got it. Had to change my factorial to double.