Compilare: main.cpp: In function 'int main()': main.cpp:20:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sol.size();i++) ~^~~~~~~~~~~ main.cpp:30:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<sol.size();i++) ~^~~~~~~~~~~