View Compilation Error

0_0_24532851_11227.cpp: In function 'int main()':
0_0_24532851_11227.cpp:13:25: error: cannot pass objects of non-trivially-copyable type 'std::string {aka class std::basic_string<char>}' through '...'
         scanf("%s%s",a,b);
                         ^
0_0_24532851_11227.cpp:13:25: error: cannot pass objects of non-trivially-copyable type 'std::string {aka class std::basic_string<char>}' through '...'
0_0_24532851_11227.cpp:14:23: error: cannot convert 'std::string {aka std::basic_string<char>}' to 'const char*' for argument '1' to 'size_t strlen(const char*)'
         int n=strlen(a);
                       ^