#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
char t[2][2][2] = {'0','1','2','3','4','5','6','7'};
#define z(s,n) (s[n]=='0')?0:1
#define B(s) t[z(s,0)][z(s,1)][z(s,2)]
int main(void)
{
FILE *f;long l,a;char *b,*n;int i,j=0;
f=fopen("i","r");
fseek(f,0,SEEK_END);
l=ftell(f);
fseek(f,0,SEEK_SET);
b=calloc(1,l+1);
a=((l-1)/3)+((((l-1)%3)>0)?1:0);
n=calloc(1,a+1);
fgets(b,l,f);
fclose(f);

n[a] = 0;
for(i=l-4;i>-1;i-=3)
{
n[(a-1)-(j++)]=B((&b[i]));
if(i>0)b[i] = 0;
}

if(i==-2)n[0]=t[0][0][z(b,0)];
if(i==-1)n[0]=t[0][z(b,1)][z(b,0)];

f=fopen("o","w");
fputs(n,f);
fclose(f);
return 0;
}