View Compilation Error

0_0_39504988_19435.cpp: In function 'int main()':
0_0_39504988_19435.cpp:49:39: error: invalid conversion from 'const char*' to 'int' [-fpermissive]
   49 |                         if(day<10) day+="0";
      |                                    ~~~^~~~~
      |                                       |
      |                                       const char*