f1_score.c

#define eq(X, a) ((X[0] == a[0]) && (X[1] == a[1]))

main() {
  int t;
  float tp, tn, fp, fn, p, r;
  tp = tn = fp = fn = 0;
  char c[3];
  scanf("%d\n", &t);

  while (t--) {
    gets(c);
    if (eq(c, "++")) tp++;
    if (eq(c, "+-")) fn++;
    if (eq(c, "-+")) fp++;
    if (eq(c, "--")) tn++;
  }

  p = tp / (tp + fp);
  r = tp / (tp + fn);

  printf("%.2f", 2*p*r / (p+r));

  return 0;
}