Compilare: main.cpp: In function 'void dfs(long long int, long long int)': main.cpp:15:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<val.size(); i++) ~^~~~~~~~~~~ main.cpp:23:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<val.size(); i++) ~^~~~~~~~~~~ main.cpp: In function 'void dfs2(long long int, long long int)': main.cpp:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<val.size(); i++) ~^~~~~~~~~~~ main.cpp: In function 'long long int calc(long long int)': main.cpp:38:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<val.size(); i++) ~^~~~~~~~~~~