Compilare: main.cpp: In function 'int main()': main.cpp:11:26: warning: comparison of integer expressions of different signedness: 'long long unsigned int' and 'int' [-Wsign-compare] 11 | for(F>>n>>k,--k,k>=(1<<(n-2))?k-=(1LL<<(n-2)),s[0]='b',s[n-1]='b':(s[0]='a',s[n-1]='a'),i=n-1;k;s[--i]=(k&1?'b':'a'),k>>=1); | ~^~~~~~~~~~~~