//interactive
ll@N;string S(N,97),T=S;wt("?",T);ll@n,a=0,b;rep[T,i](t,N){b=1;REP(c,98,122+(i<N-1)){t=c;wt("?",T);t=97;ll@m;if(m>n)S[i]=c,b=0,break;}if(b&&a++<n&&i>N-2)S[i]='z';}wt("!",S);