Compilare: main.cpp: In function 'int dfs1(int)': main.cpp:19:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a[k].size() && sol!=-1; i++) ~^~~~~~~~~~~~ main.cpp: In function 'void dfs(int, int)': main.cpp:48:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[k].size(); i++) ~^~~~~~~~~~~~ main.cpp:57:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[k].size(); i++) ~^~~~~~~~~~~~ main.cpp:67:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[k].size(); i++) ~^~~~~~~~~~~~ main.cpp:76:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<g[k].size(); i++) ~^~~~~~~~~~~~