/in/foo.cc: In function 'int main()':
/in/foo.cc:8:16: warning: too many arguments for format [-Wformat-extra-args]
    8 |         printf("x+y",x,y);
      |                ^~~~~
/in/foo.cc:9:16: error: 'o' was not declared in this scope
    9 |         return o;
      |                ^