#include <bits/stdc++.h>
int main() {
  int TUX;
  scanf("%d", &TUX);
  int FOO = 0, BAR = 0, BAZ = 0, QUZ = 1;
  while (TUX != 0) {
    int PUR;
    scanf("%d", &PUR);
    FOO = FOO + PUR;
    BAR = BAR + 1;
    if (FOO * QUZ >= BAR * BAZ) {
      BAZ = FOO;
      QUZ = BAR;
    } else
      break;
    TUX--;
  }
  printf("%f\n", (BAZ * 1.0) / QUZ);
  return 0;
}
