Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:22:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ user.cpp:25:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[nr].size();j++) ~^~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:46:13: warning: unused variable ‘j’ [-Wunused-variable] int n,i,j,a,b,m,x; ^ user.cpp:46:21: warning: unused variable ‘x’ [-Wunused-variable] int n,i,j,a,b,m,x; ^ user.cpp:44:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.in","r",stdin); ^ user.cpp:45:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.out","w",stdout); ^