#include<bits/stdc++.h>

 #define LL long long

 #define N 100005

 #define lowbit(x) x&(-x)

 using namespace std;

 inline int ra()

 {

     int x=,f=; char ch=getchar();

     while (ch<'' || ch>'') {if (ch=='-') f=-; ch=getchar();}

     while (ch>='' && ch<='') {x=x*+ch-''; ch=getchar();}

     return x*f;

 }

 LL n,m=,ans;

 string s;

 LL get(int l, int r)// int boom!!

 {

     LL sum=;

     for (int i=l; i<=r; i++)

     {

         sum=sum*+s[i]-'';

         if (sum>n) break;

     }

     return sum;

 }

 int main()

 {

     n=(LL)ra(); cin>>s;

     int len=s.length();

     int last=len-,i=len-;

     while (i!=-)

     {

         if (s[i]!='' && get(i,last)<n)

         {

             i--;

             if (i==-)

             {

                 ans+=m*get(,last);

                 break;

             }

             continue;

         }

         if (s[i]=='')

         {

             int j=i;

             while (j!=- && get(j,last)<n && s[j]=='') j--;

             while (s[last]=='' && get(j,last)>=n) m=m*n,last--;

             if (s[j]!='' && get(j,last)<n) i=j;

             if (s[j]!='' && get(j,last)>=n)

             {

                 ans+=m*get(i,last);

                 last=i;

                 m=m*n;

             }

         }

         if (s[i]!='' && get(i,last)>=n)

         {

             ans+=m*get(i+,last);

             last=i;

             m*=n;

         }

     }

     cout<<ans;

     return ;

 }