#include<bits/stdc++.h>
int num[192] = {0,0,1,2,3,4,5,6,7,8,9,1,0,1,1,1,2,1,3,1,4,1,5,1,6,1,7,1,8,1,9,2,0,2,1,2,2,2,3,2,4,2,5,2,6,2,7,2,8,2,9,3,0,3,1,3,2,3,3,3,4,3,5,3,6,3,7,3,8,3,9,4,0,4,1,4,2,4,3,4,4,4,5,4,6,4,7,4,8,4,9,5,0,5,1,5,2,5,3,5,4,5,5,5,6,5,7,5,8,5,9,6,0,6,1,6,2,6,3,6,4,6,5,6,6,6,7,6,8,6,9,7,0,7,1,7,2,7,3,7,4,7,5,7,6,7,7,7,8,7,9,8,0,8,1,8,2,8,3,8,4,8,5,8,6,8,7,8,8,8,9,9,0,9,1,9,2,9,3,9,4,9,5,9,6,9,7,9,8,9,9,1};
main(){
    int N;
    scanf("%d",&N);
    for(int i = 0;i < 192;i++){
        num[i] *= N;
    }
    for(int i = 191;i > 0;i--){
        num[i-1] += num[i]/10;
        num[i] %= 10;
    }
    if(num[0])printf("%d",num[0]);
    printf("%d.",num[1]);
    for(int i = 2;i < 192;i++){
        printf("%d",num[i]);
    }
    printf("\n");
}