#include <bits/stdc++.h>
using namespace std;
template <typename T1, typename T2>
inline void chkmin(T1 &x, T2 y) {
  if (x > y) x = y;
}
template <typename T1, typename T2>
inline void chkmax(T1 &x, T2 y) {
  if (x < y) x = y;
}
inline int readChar();
template <class T = int>
inline T readInt();
template <class T>
inline void writeInt(T x, char end = 0);
inline void writeChar(int x);
inline void writeWord(const char *s);
static const int buf_size = 4096;
inline int getChar() {
  static char buf[buf_size];
  static int len = 0, pos = 0;
  if (pos == len) pos = 0, len = fread(buf, 1, buf_size, stdin);
  if (pos == len) return -1;
  return buf[pos++];
}
inline int readChar() {
  int c = getChar();
  while (c <= 32) c = getChar();
  return c;
}
template <class T>
inline T readInt() {
  int s = 1, c = readChar();
  T x = 0;
  if (c == '-') s = -1, c = getChar();
  while ('0' <= c && c <= '9') x = x * 10 + c - '0', c = getChar();
  return s == 1 ? x : -x;
}
static int write_pos = 0;
static char write_buf[buf_size];
inline void writeChar(int x) {
  if (write_pos == buf_size)
    fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
  write_buf[write_pos++] = x;
}
template <class T>
inline void writeInt(T x, char end) {
  if (x < 0) writeChar('-'), x = -x;
  char s[24];
  int n = 0;
  while (x || !n) s[n++] = '0' + x % 10, x /= 10;
  while (n--) writeChar(s[n]);
  if (end) writeChar(end);
}
inline void writeWord(const char *s) {
  while (*s) writeChar(*s++);
}
struct Flusher {
  ~Flusher() {
    if (write_pos) fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
  }
} flusher;
const int INF = 2000000000;
int n;
string k;
int l;
bool can[62][62];
int prev228[62][62];
int who[62][62];
int main() {
  cin >> n >> k;
  l = (int)(k).size();
  for (int i = 0; i < l; i++) {
    long long cur = 0;
    for (int j = i; j < l; j++) {
      if (cur != INF) {
        cur *= 10LL;
        cur += k[j] - '0';
      }
      cur = min(cur, 1LL * n);
      who[i][j] = cur;
    }
  }
  long long ans = 0;
  for (int i = 1; i <= l; i++) {
    for (int j = l - 1; j >= 0; j--) {
      if (i == 1) {
        if (k[j] == '0' && j != l - 1) {
          continue;
        }
        if (who[j][l - 1] < n) {
          can[i][j] = 1;
          prev228[i][j] = l;
        }
        continue;
      }
      for (int j1 = j; j1 < l; j1++) {
        if (who[j][j1] < n && can[i - 1][j1 + 1]) {
          if (k[j] == '0' && j1 - j != 0) {
            continue;
          }
          can[i][j] = 1;
          prev228[i][j] = j1 + 1;
          break;
        }
      }
    }
    if (can[i][0]) {
      int cur = 0;
      int i1 = i;
      while (cur < l) {
        int cp = 0;
        for (int t = cur; t < prev228[i1][cur]; t++) {
          cp *= 10;
          cp += k[t] - '0';
        }
        ans *= n;
        ans += cp;
        cur = prev228[i1][cur];
        i1--;
      }
      break;
    }
  }
  cout << ans << endl;
  return 0;
}
