/in/foo.cc: In function 'int main()':
/in/foo.cc:45:9: warning: this 'while' clause does not guard... [-Wmisleading-indentation]
         while(son[f[x][0]]==x)x=f[x][0];y=x;
         ^~~~~
/in/foo.cc:45:41: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'while'
         while(son[f[x][0]]==x)x=f[x][0];y=x;
                                         ^
/in/foo.cc:48:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=1,y=x;j<v1[x].size();j++)
                         ~^~~~~~~~~~~~~