/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:18:20: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
    for(int i=1;i=n+1;i++)
                    ^
/in/foo.cc:23:12: warning: statement has no effect [-Wunused-value]
        a[x]==i;   
        ~~~~^~~
/in/foo.cc:30:1: error: a function-definition is not allowed here before '{' token
 {
 ^
/in/foo.cc:34:1: error: expected '}' at end of input
 }
 ^