import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }

string COLOR(string s = "") { return "\x1b[" ~ s ~ "m"; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


debug {
enum A = 4;
} else {
enum A = 26;
}

int ask(char[] cs) {
  writeln("? ", cs); stdout.flush;
  const res = readInt;
  return res;
}

void main() {
  const N = readInt;
  auto cs = new char[N];
  cs[] = 'a';
  const base = ask(cs);
  
  auto ans = new char[N];
  ans[] = cast(char)('a' + (A - 1));
  foreach (i; 0 .. N) {
    auto fs = new int[A - 1];
    fs[0] = base;
    foreach (a; 1 .. A - 1) {
      cs[i] = cast(char)('a' + a);
      fs[a] = ask(cs);
      cs[i] = 'a';
    }
    const minF = fs.minElement;
    foreach (a; 0 .. A - 1) if (minF < fs[a]) {
      ans[i] = cast(char)('a' + a);
    }
  }
  writeln("! ", ans); stdout.flush;
}