foo.cc:21:10: error: '::main' must return 'int'
 int main()
          ^
foo.cc: In function 'int main()':
foo.cc:24:27: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
 while(scanf("%d%d", &n, &m) != EOF)
                     ~~    ^
foo.cc:24:27: warning: format '%d' expects argument of type 'int*', but argument 3 has type 'long long int*' [-Wformat=]
foo.cc:37:29: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long int*' [-Wformat=]
   scanf("%d%d%d", &x, &y, &z);
                   ~~        ^
foo.cc:37:29: warning: format '%d' expects argument of type 'int*', but argument 3 has type 'long long int*' [-Wformat=]
foo.cc:37:29: warning: format '%d' expects argument of type 'int*', but argument 4 has type 'long long int*' [-Wformat=]
foo.cc:37:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d", &x, &y, &z);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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