#include <iostream> #include <cstring> using namespace std; int main(){ char str[64]; int r; cin>>r>>str; long long len=strlen(str),x=1,s=0,t; for(int i=len-1;i>=0;i--){ if(str[i]>='A') t=str[i]-'A'+10; else t=str[i]-'0'; s+=t*x; x*=r; } cout<<s; return 0; }