#include <stdio.h>

long long int conv(int num[11],int max);

int main(){
  int num[11],c,i=0,max=0;
    printf("Input numbers 0-9 and letters A-F\n(String length must be less or equal to 10 symbols)\n");
    while((c=getchar())!=EOF){
       if(c>='A' && c<='F'){
        num[i]=c-'A'+10;
        i++;
       }
       if(c>='0' && c<='9') {
            num[i]=c-'0';
            i++;
         }
         max=i;
   }
   if(max>10) printf("Input is too long\n");
   else printf("%lli\n",conv(num,max));
}


long long int conv(int num[11],int max){
  int k,j;
  long long int s=0;
  long long int multi[]={1,16,256,4096,65536,1048576,16777216,268435456,4294967296,68719476736,1099511627776};
    for(j=0;j<max;j++){
         s=s+num[j]*multi[max-j-1];
    }
    return s;
}