#include<stdio.h>
#include<math.h>

int main()
{
    int P = 2;
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);
    scanf("%d", &P);
    int x;
    for(x = 1;x < 8;x++)
    {
        if(P > ((int)pow(10,1)))
        P--;
        else break;
    }

    int fact = (P * 5);
    if(P < 1)
    {fact = 0;fact--;

    }
    else
     if(P > ((int)pow(10,8)))
     {fact = 0;fact--;

    }printf("%d\n", fact);
    return 0;
}