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

void approx(int z, int n, int nmax, int *za, int *na) {
  int z0 = 0, n0 = 1, z1 = 1, n1 = 0, q, t;
  double soll = (double)z / n;

  // Kettenbruchentwicklung

  while (n) {
    q = z / n;

    t = z - q * n;
    z = n;
    n = t;

    t = q * n1 + n0;
    if (t > nmax)
      break;

    n0 = n1;
    n1 = t;

    t = q * z1 + z0;
    z0 = z1;
    z1 = t;
  }

  q = (nmax - n0) / n1;
  z0 = q * z1 + z0;
  n0 = q * n1 + n0;

  // z1/n1 ist der beste (Haupt-)Näherungbruch, z0/n0 der beste
  // Nebennäherungsbruch. Besten von beiden als Ergebnis liefern:

  if (  fabs((double)z1 / n1 - soll)
      < fabs((double)z0 / n0 - soll) ) {
    *za = z1;
    *na = n1;
  }
  else {
    *za = z0;
    *na = n0;
  }
}

int main(int argc, char **argv) {
  int z    = atoi(argv[1]),
      n    = atoi(argv[2]),
      nmax = atoi(argv[3]);
  int za, na;

  approx(z, n, nmax, &za, &na);
  printf("%d/%d\n", za, na);

  return 0;
}