foo.cc: In function 'int main()':
foo.cc:20:57: warning: format '%s' expects argument of type 'char*', but argument 4 has type 'char (*)[20]' [-Wformat=]
   scanf("%d %s %s %d",&s[i].bh,s[i].mz,&s[i].hm,&s[i].sj); 
                                        ~~~~~~~~         ^
foo.cc:20:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %s %s %d",&s[i].bh,s[i].mz,&s[i].hm,&s[i].sj); 
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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