foo.cc:4:1: error: expected ',' or ';' before 'int'
 int n,t;
 ^~~
foo.cc: In function 'void dfs(int, int)':
foo.cc:7:9: error: 'n' was not declared in this scope
  if(sum>n)
         ^
foo.cc:10:2: error: expected primary-expression before 'else'
  else{
  ^~~~
foo.cc:10:2: error: return-statement with a value, in function returning 'void' [-fpermissive]
foo.cc:10:2: error: expected ';' before 'else'
foo.cc:10:2: error: 'else' without a previous 'if'
foo.cc:12:3: error: expected ';' before 'dfs'
   dfs(num+,sum)
   ^~~
foo.cc:15:1: error: a function-definition is not allowed here before '{' token
 {
 ^
foo.cc:29:1: error: expected '}' at end of input
 }
 ^

[Hydro](https://hydro.ac)提供评测服务