foo.c:3:1: error: unknown type name 'using'
3 | using namespace std;
| ^~~~~
foo.c:3:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
3 | using namespace std;
| ^~~
foo.c: In function 'main':
foo.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
8 | scanf("%s",a);
| ^~~~~~~~~~~~~
foo.c:9:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
9 | scanf("%s",b);
| ^~~~~~~~~~~~~
[Hydro](https://hydro.ac)提供评测服务