#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<vector> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; char n(char x){ if(x>=65) return 10+x-'A'; else return x-'0'; } int main(){ int r,sum=0,s=1; string a; cin>>r>>a; for(int i=a.size()-1;i>=0;i--){ sum+=(n(a[i]))*s; s*=r; } cout<<sum; return 0; }