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

double f(double x) { return x * x; }

int main() {
  double a = 0, b = 1;
  int n = 10;
  double h = (b - a) / n;
  double sum = (f(a) + f(b)) / 2;
  for (int i = 1; i < n; i++) {
    sum += f(a + i * h);
  }
  double integral = h * sum;
  printf("Integral of x^2 over [0,1] = %.6f\n", integral);
  printf("Exact value = %.6f\n", 1.0 / 3);
  return 0;
}