      
    HAI  
    I HAS A TUX  
    GIMMEH TUX  
    I HAS A FOO ITS 0  
    I HAS A BAR ITS 0  
    I HAS A BAZ ITS 0  
    I HAS A QUZ ITS 1  
    TUX IS NOW A NUMBR  
    IM IN YR LOOP NERFIN YR TUX TIL BOTH SAEM TUX AN 0  
    I HAS A PUR  
    GIMMEH PUR  
    PUR IS NOW A NUMBR  
    FOO R SUM OF FOO AN PUR  
    BAR R SUM OF BAR AN 1  
    BOTH SAEM BIGGR OF PRODUKT OF FOO AN QUZ AN PRODUKT OF BAR BAZ AN PRODUKT OF FOO AN QUZ  
    O RLY?  
    YA RLY  
    BAZ R FOO  
    QUZ R BAR  
    OIC  
    IM OUTTA YR LOOP  
    BAZ IS NOW A NUMBAR  
    VISIBLE SMOOSH QUOSHUNT OF BAZ QUZ  
    KTHXBYE  
    

Input

The input contains between 1 and 10 lines, i-th line contains an integer number xi (0 ≤ xi ≤ 9).

Output

Output a single real number. The answer is considered to be correct if its absolute or relative error does not exceed 10 - 4.

Examples

Input

3
0
1
1


Output

0.666667
#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int re = 0;
  bool f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == -1) return -1;
    if (c == '-') f = 0;
    c = getchar();
  };
  while (c >= '0' && c <= '9') {
    ;
    ;
    re = re * 10 + c - '0';
    c = getchar();
  };
  return f ? re : -re;
}
inline long long readll() {
  long long re = 0;
  bool f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == -1) return -1;
    if (c == '-') f = 0;
    c = getchar();
  };
  while (c >= '0' && c <= '9') {
    ;
    ;
    re = re * 10 + c - '0';
    c = getchar();
  };
  return f ? re : -re;
}
inline double readd() {
  double a = 0, b = 0;
  bool f = 1;
  char c = getchar();
  while (c > '9' || c < '0') {
    if (c == -1) return -1;
    if (c == '-') f = 0;
    c = getchar();
  };
  while (c >= '0' && c <= '9') {
    ;
    ;
    a = a * 10 + c - '0';
    c = getchar();
  };
  if (c == '.') {
    int cnt = 0;
    c = getchar();
    while (c >= '0' && c <= '9') {
      ++cnt;
      b = b * 10 + c - '0';
      c = getchar();
    };
    while (cnt--) b = b / 10;
  }
  return f ? (a + b) : -(a + b);
}
inline void write(long long x) {
  if (x == 0) return (void)putchar('0');
  if (x < 0) putchar('-'), x = -x;
  static char buf[30];
  char* p = buf;
  while (x) {
    *(p++) = x % 10 + '0';
    x /= 10;
  }
  while (p > buf) putchar(*(--p));
}
inline int readstr(char* s) {
  char* begin = s;
  char c = getchar();
  while (c <= 32 || c > 126) c = getchar();
  while (c > 32 && c <= 126) {
    *s++ = c;
    c = getchar();
  }
  *s = 0;
  return s - begin;
}
int main() {
  int TUX = read();
  int FOO = 0, BAR = 0, BAZ = 0, QUZ = 1;
  for (int i = 1; i <= TUX; i++) {
    int PUR = read();
    FOO += PUR;
    BAR++;
    if (FOO * QUZ > BAZ * BAR) {
      BAZ = FOO;
      QUZ = BAR;
    }
  }
  printf("%lf", (double)BAZ / QUZ);
  return 0;
}
