>>803
#include <stdio.h>
#include <math.h>

double f(double x) { return sqrt(4 - x * x); }

int main(void)
{
int i, n;
double r = 2.0, h, s;

for(n = 100; n <= 100000; n *= 10) {
h = r / n;
for(s = 0.0, i = 0; i < n; i++) s += (f(i * h) + f((i + 1) * h)) * h / 2;
printf("n = %-6d %f\n", n, s);
}

return 0;
}