/in/foo.cc: In function 'void dfs(int, int, int, int)':
/in/foo.cc:6:20: error: expected primary-expression before '/' token
     if (a == 10) { /
                    ^
/in/foo.cc:7:9: error: expected primary-expression before 'if'
         if (b + c == n || c - b == n) {
         ^~
/in/foo.cc:16:12: error: a function-definition is not allowed here before '{' token
 int main() {
            ^
/in/foo.cc:21:1: error: expected '}' at end of input
 }
 ^