foo.cc: In function ‘int main()’:
foo.cc:13:15: warning: ‘maxn’ may be used uninitialized [-Wmaybe-uninitialized]
   13 |         cout<<maxn;
      |               ^~~~
foo.cc:5:19: note: ‘maxn’ was declared here
    5 |         int a,b,c,maxn;
      |                   ^~~~