foo.cc: In function 'bool check(char)':
foo.cc:44:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
foo.cc: In function 'int main()':
foo.cc:47:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d\n",&n,&m);
     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:52:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%c",&a[i][j]);
             ~~~~~^~~~~~~~~~~~~~~
foo.cc:60:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s",lu);
     ~~~~~^~~~~~~~~
foo.cc:70:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&t);
     ~~~~~^~~~~~~~~

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