Compilare: main.cpp: In function 'int main()': main.cpp:159:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<how_many[a][b].size();i++) ~^~~~~~~~~~~~~~~~~~~~~~ main.cpp:51:25: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&n); ^ main.cpp:53:44: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d%d",&v[i].x,&v[i].y); ^ main.cpp:56:25: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&t); ^