Compilare: main.cpp: In function 'int main()': main.cpp:45:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < mch[i].size() ; j ++){ ~~^~~~~~~~~~~~~~~ main.cpp:30:25: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d",&n); ^ main.cpp:32:34: warning: ignoring return value of 'int fscanf(FILE*, const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] fscanf (fin,"%d%d",&x,&y); ^