foo.cc: In function 'int main()':
foo.cc:22:40: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=2;i<=n;i++){ int u; scanf("%d", &u); rson[i]=lson[u]; lson[u]=i; }
                                   ~~~~~^~~~~~~~~~
foo.cc:23:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;i++) scanf("%d", &c[i]);
                           ~~~~~^~~~~~~~~~~~~
foo.cc:24:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(int i=1;i<=n;i++) scanf("%d", &e[i]);
                           ~~~~~^~~~~~~~~~~~~

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