#include <stdio.h>

int main() {
    
    int n, i, digit;
    scanf("%d", &n);
    
    if (n <= 0) {
        printf("Invalid input");
        return 0;
    }
    
    int arr[n];
    while (n > 0){
        digit = n % 10;
        arr[i] = digit;
        n /= 10;
        i++;
    }
    
    int median = arr[0] / arr[n];
    
    printf("%.2f", median);
    return 0;
    
    
}