#include <bits/stdc++.h>
int main() {
  float a, b, c, d;
  int ansnum, ansden;
  scanf("%f%f%f%f", &a, &b, &c, &d);
  if ((a / b) > (c / d)) {
    ansden = a * d;
    ansnum = c * b;
  } else {
    ansden = b * c;
    ansnum = d * a;
  }
  for (int i = 2; i <= ansnum; i++) {
    if (ansnum % i == 0 && ansden % i == 0) {
      ansnum /= i;
      ansden /= i;
      i--;
      continue;
    }
  }
  printf("%d/%d", ansden - ansnum, ansden);
  return 0;
}
