Compilare: main.cpp: In function 'int main()': main.cpp:21:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<s[i-1].size()&&j<s[j].size()&&s[i-1][j]==s[i][j];j++); ~^~~~~~~~~~~~~~ main.cpp:21:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<s[i-1].size()&&j<s[j].size()&&s[i-1][j]==s[i][j];j++); ~^~~~~~~~~~~~