foo.c: In function 'main':
foo.c:16:6: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
      if(flag1==2)
      ^~
foo.c:18:7: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
       flag1=0;
       ^~~~~
foo.c:21:3: error: expected '}' before 'else'
   else if(N=2)
   ^~~~
foo.c:21:11: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
   else if(N=2)
           ^
foo.c:6:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&N);
  ^~~~~~~~~~~~~~~~~~~~

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