foo.cc: In function 'int diffSet(int*, int, int*, int, int*)':
foo.cc:84:9: warning: variable 'n4' set but not used [-Wunused-but-set-variable]
     int n4;
         ^~
foo.cc: In function 'int symmDiffSet(int*, int, int*, int, int*)':
foo.cc:108:13: warning: variable 'n4' set but not used [-Wunused-but-set-variable]
  int i,n3=0,n4;
             ^~
foo.cc: In function 'int main()':
foo.cc:136:15: warning: unused variable 'i' [-Wunused-variable]
  int n1,n2,n3,i,j;
               ^
foo.cc:136:17: warning: unused variable 'j' [-Wunused-variable]
  int n1,n2,n3,i,j;
                 ^

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