foo.cc: In function 'void get_sg()':
foo.cc:33:19: warning: logical not is only applied to the left hand side of comparison [-Wlogical-not-parentheses]
         if(!vis[j]==i)
                   ^~
foo.cc:33:12: note: add parentheses around left hand side expression to silence this warning
         if(!vis[j]==i)
            ^~~~~~~
            (      )
foo.cc: In function 'int main()':
foo.cc:44:5: warning: label 'std' defined but not used [-Wunused-label]
     std:ios::sync_with_stdio(false);
     ^~~

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