Compilare: main.cpp: In function 'int main()': main.cpp:42:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < comp.size(); i++) ~~^~~~~~~~~~~~~ main.cpp:46:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < comp.size(); i++) ~~^~~~~~~~~~~~~ main.cpp:48:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < comp.size(); i++) { ~~^~~~~~~~~~~~~ main.cpp:59:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < comp.size(); i++) ~~^~~~~~~~~~~~~ main.cpp:64:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < comp.size(); i++) { ~~^~~~~~~~~~~~~ main.cpp:65:32: warning: 'ultima' may be used uninitialized in this function [-Wmaybe-uninitialized] if(i == prima || i == ultima) continue; ~~^~~~~~~~~ main.cpp:51:35: warning: 'prima' may be used uninitialized in this function [-Wmaybe-uninitialized] cout << comp[prima].back() << ' ' << comp[i][0] << '\n'; ^