Compilare: main.cpp: In function 'int main()': main.cpp:38:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2;i<v.size();++i) ~^~~~~~~~~ main.cpp:48:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<dummy.size();++i) ~^~~~~~~~~~~~~ main.cpp:52:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<dummy.size();++i) ~^~~~~~~~~~~~~ main.cpp:57:36: warning: format '%d' expects argument of type 'int', but argument 3 has type 'std::vector<std::pair<int, int> >::size_type {aka long unsigned int}' [-Wformat=] fprintf(fout,"%d\n", sol.size()); ^ main.cpp:58:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<sol.size();++i) ~^~~~~~~~~~~ main.cpp: In function 'void dfs(int)': main.cpp:65:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,to;i<g[node].size();++i){ ~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:20:30: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d",&n,&m); ^ main.cpp:22:34: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d",&x,&y); ^