#include <stdio.h>

#if 0

void printh(int hex, int n){
    for(int i=n-2;i>=1;i--){
        printf("%x", (hex>>4*i)&0xf);
    }
}

int main() {
    int hex = 0xA123;
    int b = hex;
    int count = 0;

    while(b!=0){
        count++;
        b=b>>4;
    }

    printf("%d\n",count);
    printh(hex,count);
}
#endif

void printb(int bin, int n){
    for(int i=n-2;i>=1;i--){
        printf("%d", (bin>>1*i)&0b1);
    }
}

int main(){
    int bin = 0b010101;
    int cp = bin;
    int count = 0;

    while(cp!=0){
        count++;
        cp=cp>>1;
    }

    printf("%d\n",count);
    printb(bin, count);
}