foo.cc: In function ‘int main()’:
foo.cc:12:16: warning: ‘c’ may be used uninitialized [-Wmaybe-uninitialized]
   12 |         cout<<c+b+a-1;
      |               ~^~
foo.cc:5:23: note: ‘c’ was declared here
    5 |         int n,a=1,b=1,c;
      |                       ^