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

#define EPS 0.0000000001

double a = 7.0;

int main(void)
{
int n = 1;
double s = 1, ds = 1;

do {
ds /= n;
ds *= a;
n++;
s += ds;
} while (fabs(ds) > EPS);

printf("e^%g = %.15g\n", a, s);

return 0;
}