/in/foo.cc: In function 'void get_sg()':
/in/foo.cc:28:19: warning: logical not is only applied to the left hand side of comparison [-Wlogical-not-parentheses]
         if(!vis[j]==i)
                   ^~
/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:38:16: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
     if(sg[1]==0&&way==1||sg[1]&&way==0){
        ~~~~~~~~^~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:53:5: warning: label 'std' defined but not used [-Wunused-label]
     std:ios::sync_with_stdio(false);
     ^~~