/in/foo.cc: In function 'void dfs(int)':
/in/foo.cc:30:37: warning: this 'else' clause does not guard... [-Wmisleading-indentation]
     if(k==n-1)if(check())out();else;else;
                                     ^~~~
/in/foo.cc:31:9: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'else'
         for(int i=1;i<n;i++)if(v[i]==-1)v[i]=k,dfs(k+1),v[i]=-1;
         ^~~