/* 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
contest
son
---+/
/+---test
contest
programming
---+/
/+---test
contest
sentence
---+/

void main(string[] args) {
  const S = readln.chomp;
  const T = readln.chomp;

  size_t t_consumed;
  size_t last_consumed_index;

  size_t i;
  foreach (c; S.cycle()) {
    if (t_consumed >= T.length) {
      i.writeln;
      return;
    }
    if (c == T[t_consumed]) {
      ++t_consumed;
      last_consumed_index = i;
    }
    if (i-last_consumed_index >= S.length) {
      (-1).writeln;
      return;
    }
    ++i;
  }
}
