Compilare: user.cpp: In function ‘int main()’: user.cpp:51:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j; ^ user.cpp:54:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d", &N, &M); ^ user.cpp:56:44: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d %d", &x, &y, &c); ^