foo.cc: In function 'int isExist(int*, int, int)':
foo.cc:36:7: warning: statement has no effect [-Wunused-value]
   flag==1;
   ~~~~^~~
foo.cc: In function 'int main()':
foo.cc:62:15: warning: unused variable 'i' [-Wunused-variable]
  int n1,n2,n3,i;
               ^
foo.cc: In function 'int bj(int*, int, int*, int, int*)':
foo.cc:52:3: warning: 'flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(flag==0)
   ^~
foo.cc: In function 'int main()':
foo.cc:52:3: warning: 'flag' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(flag==0)
   ^~
foo.cc:51:7: note: 'flag' was declared here
   int flag;
       ^~~~

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