import std.stdio, std.conv, std.array, std.string, std.algorithm, std.container, std.range, core.stdc.stdlib, std.math, std.typecons;
T[][] combinations(T)(T[] s, in int m) {   if (!m) return [[]];   if (s.empty) return [];   return s[1 .. $].combinations(m - 1).map!(x => s[0] ~ x).array ~ s[1 .. $].combinations(m); }

void main() {
  auto size = readln.chomp.to!int;
  auto lucky = cast(byte[])readln.chomp;
  lucky[] -= '0';

  void solve() {
    int count;
    foreach(x; 0..10) foreach(y; 0..10) foreach(z; 0..10) {
      if (!lucky.canFind(x)) continue;
      auto after = lucky.findSplitAfter([x]);
      if (!after[1].canFind(y)) continue;
      after = after[1].findSplitAfter([y]);
      if (!after[1].canFind(z)) continue;
      count++;
    }
    writeln(count);
  }

  solve();
}
