/* imports all std modules {{{*/
import
  std.algorithm,
  std.array,
  std.ascii,
  std.base64,
  std.bigint,
  std.bitmanip,
  std.compiler,
  std.complex,
  std.concurrency,
  std.container,
  std.conv,
  std.csv,
  std.datetime,
  std.demangle,
  std.encoding,
  std.exception,
  std.file,
  std.format,
  std.functional,
  std.getopt,
  std.json,
  std.math,
  std.mathspecial,
  std.meta,
  std.mmfile,
  std.net.curl,
  std.net.isemail,
  std.numeric,
  std.parallelism,
  std.path,
  std.process,
  std.random,
  std.range,
  std.regex,
  std.signals,
  std.socket,
  std.stdint,
  std.stdio,
  std.string,
  std.system,
  std.traits,
  std.typecons,
  std.uni,
  std.uri,
  std.utf,
  std.uuid,
  std.variant,
  std.zip,
  std.zlib;
/*}}}*/

/+---test
10
ZABCDBABCQ
---+/
/+---test
33
ABCCABCBABCCABACBCBBABCBCBCBCABCB
---+/

void main(string[] args) {
  const N = readln.chomp.to!long;
  const S = readln.chomp;

  long ans;
  long offset;
  while (true) {
    const x  = S[offset..$].indexOf("ABC");
    if (x == -1) break;
    offset += x + 1;
    ++ans;
  }
  ans.writeln;
}
