#include <stdio.h>
#include <string.h>

void uint2str(char str[], size_t len, int num) {
    snprintf(str, len, "%d", num);
}

void main(void){
    char champernowne[200] = "0.";
    for(int i = 1 ; i <= 55 ; i++){
        char numText[100] = "a";
        uint2str(numText,100,i);
        strcat(champernowne, numText);
    }
    int n = 0;
    scanf("%d",&n);
    printf("%c",champernowne[n+1]);
}