foo.cc: In function 'int main()':
foo.cc:52:21: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long int*' [-Wformat=]
     scanf("%d", &len);
                 ~~~~^
foo.cc:53:21: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long int*' [-Wformat=]
     scanf("%d\n", &n);
                   ~~^
foo.cc:58:50: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long int*' [-Wformat=]
         scanf("%d %c %d %c\n", &a, &ch1, &b, &ch2);
                                ~~                ^
foo.cc:58:50: warning: format '%d' expects argument of type 'int*', but argument 4 has type 'long int*' [-Wformat=]
foo.cc:52:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &len);
     ~~~~~^~~~~~~~~~~~
foo.cc:53:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d\n", &n);
     ~~~~~^~~~~~~~~~~~
foo.cc:58:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %c %d %c\n", &a, &ch1, &b, &ch2);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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