/in/foo.cc: In function 'int main()':
/in/foo.cc:7:20: error: request for member 'size' in 'st', which is of non-class type 'int'
  for(int i=0;i<=st.size();i++)
                    ^~~~
/in/foo.cc:9:10: error: invalid types 'int[int]' for array subscript
   if(st[i]>='0'&&st[i]<='9')
          ^
/in/foo.cc:9:22: error: invalid types 'int[int]' for array subscript
   if(st[i]>='0'&&st[i]<='9')
                      ^
/in/foo.cc:10:4: error: 'ans' was not declared in this scope
    ans=ans*16+st[i]-'0';
    ^~~
/in/foo.cc:10:19: error: invalid types 'int[int]' for array subscript
    ans=ans*16+st[i]-'0';
                   ^
/in/foo.cc:12:4: error: 'ans' was not declared in this scope
    ans=ans*16+st[i]-'A'+10;
    ^~~
/in/foo.cc:12:19: error: invalid types 'int[int]' for array subscript
    ans=ans*16+st[i]-'A'+10;
                   ^
/in/foo.cc:14:8: error: 'ans' was not declared in this scope
  cout<<ans;
        ^~~