foo.cc: In function 'int main()':
foo.cc:23:17: warning: format '%s' expects argument of type 'char*', but argument 2 has type 'std::__cxx11::string {aka std::__cxx11::basic_string<char>}' [-Wformat=]
     scanf("%s",s);           //s为要处理的加密字符串，答案储存在ans里
                 ^
foo.cc:23:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s",s);           //s为要处理的加密字符串，答案储存在ans里
     ~~~~~^~~~~~~~

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