Main.cc: In function ‘int main()’: Main.cc:8:12: error: unable to find numeric literal operator ‘operator""i’ for(int i=0i<=n;i++){ ^~ Main.cc:8:12: note: use -std=gnu++11 or -fext-numeric-literals to enable more built-in suffixes Main.cc:8:21: error: expected ‘;’ before ‘)’ token for(int i=0i<=n;i++){ ^ Main.cc:15:13: error: ‘li’ was not declared in this scope for(int i=li<=r;i++){ ^~ Main.cc:15:13: note: suggested alternative: ‘i’ for(int i=li<=r;i++){ ^~ i Main.cc:15:22: error: expected ‘;’ before ‘)’ token for(int i=li<=r;i++){ ^