Compile Error
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/Scrt1.o: in function `_start': (.text+0x24): undefined reference to `main' collect2: error: ld returned 1 exit status
正在同步测试数据，请稍后 [Hydro](https://hydro.ac)提供评测服务
/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/Scrt1.o: in function `_start': (.text+0x24): undefined reference to `main' collect2: error: ld returned 1 exit status
正在同步测试数据，请稍后 [Hydro](https://hydro.ac)提供评测服务
