Compilare: user.cpp: In function ‘int main()’: user.cpp:46:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i < G[a].size();i++){ ~~^~~~~~~~~~~~~ user.cpp:47:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = i + 1;j < G[a].size();j++){ ~~^~~~~~~~~~~~~ user.cpp:21:28: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&N,&M); ^ user.cpp:24:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d %d",&x,&y); ^