Main.cc: In function 'int main()': Main.cc:6:2: error: expected ';' before 'for' for(int i=2;i<=30;i++){ ^ Main.cc:6:14: error: 'i' was not declared in this scope for(int i=2;i<=30;i++){ ^ Main.cc:6:23: error: expected ';' before ')' token for(int i=2;i<=30;i++){ ^ Main.cc:4:6: warning: unused variable 'a' [-Wunused-variable] int a=1; ^