#include <stdio.h>
#include <stdbool.h>

double approximate_pi(unsigned int steps) {
  double approximate_pi = 4.0;
  bool subtract = true;

  for(int i=2; i<=steps; i++) {
    if (subtract) {
      approximate_pi -= (4.0/(i*2-1));
    } else {
      approximate_pi += (4.0/(i*2-1));
    }
    subtract = !subtract;
  }

  return approximate_pi;
}

int main(int argc, char *argv[]) {
  // printf("sizeof(int) = %d\n", sizeof(int));
  printf("pi = %8.7f\n", approximate_pi(10000000));

  return 0;
}