foo.cc:4:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    4 | main()
      |      ^
foo.cc: In function 'int main()':
foo.cc:6:10: warning: unused variable 'r' [-Wunused-variable]
    6 |  int a,b,r,c,d,t,y=0,z=0,e=0;
      |          ^
foo.cc:6:26: warning: unused variable 'e' [-Wunused-variable]
    6 |  int a,b,r,c,d,t,y=0,z=0,e=0;
      |                          ^

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