#include <cstdio>#include <string.h>#include <algorithm>using namespace std;char a[1010],c;int sm(){int i,sum=0;for(i=0;a[i];i++)sum+=a[i]-'0';return sum;}int pt(){int j,t;t=sm();if(t%3==0){if(t){for(j=strlen(a)-1;~j;j--)printf("%c",a[j]);puts("");}else puts("0");return 1;}else return 0;}void pe(){puts("impossible");}int main(){int i,j,k,m,sum,len;scanf("%s",a);len=strlen(a);sort(a,a+len);if(a[0]=='0'){if(pt())return 0;for(i=1,sum=sm()%3;a[i]&&(a[i]-'0')%3!=sum;i++);if(!a[i]){for(;;){for(m=1;(a[m]-'0')%3==0;m++);for(j=m;a[j];j++)a[j]=a[j+1];if(pt())return 0;}}for(j=i;j<len;j++)a[j]=a[j+1];pt();return 1;}else{for(i=0;a[i]&&a[i]!='5';i++);if(!a[i]){pe();return 0;}c=a[i];a[i]=a[0];a[0]=c;sort(a+1,a+len);if(pt())return 0;for(i=1,sum=sm()%3;a[i]&&(a[i]-'0')%3!=sum;i++);if(!a[i]){for(m=1,k=0;a[m]&&((a[m]-'0')%3==0||(a[m]-'0')%3==5%3);m++)if((a[m]-'0')%3==5%3)k++;if(k==1){pe();return 1;}while(1){for(m=1;a[m]&&(a[m]-'0')%3==0;m++);if(!a[m]){pe();return 0;}for(j=m;a[j];j++)a[j]=a[j+1];if(pt())return 1;}}for(j=i;j<strlen(a);j++)a[j]=a[j+1];pt();return 1;}}
