Compilare: user.cpp: In function ‘void check()’: user.cpp:21:9: warning: unused variable ‘ok’ [-Wunused-variable] int ok=0; ^ user.cpp: In function ‘int main()’: user.cpp:68:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j; ^ user.cpp:71:32: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%lld %lld",&a,&b); ^