Compilare: main.cpp: In function 'int main()': main.cpp:62:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(comp[j].size()-1 > imp[j] && i<j) ~~~~~~~~~~~~~~~~~^~~~~~~~ main.cpp:64:60: warning: operation on 'i' may be undefined [-Wsequence-point] fout<<comp[j][imp[j]++]<<" "<<comp[i][imp[i++]]<<'\n'; ~^~ main.cpp:26:13: warning: variable 'k' set but not used [-Wunused-but-set-variable] int i,j,k,x,y; ^