Main.cc: In function ‘int main()’: Main.cc:4:2: error: ‘cin’ was not declared in this scope cin>>a; ^~~ Main.cc:4:2: note: suggested alternative: ‘main’ cin>>a; ^~~ main Main.cc:8:2: error: ‘printf’ was not declared in this scope printf("%.4lf %.4lf %.4lf",b,c,d); ^~~~~~ Main.cc:8:2: note: suggested alternative: ‘int’ printf("%.4lf %.4lf %.4lf",b,c,d); ^~~~~~ int