foo.cc: In function ‘int main()’:
foo.cc:5:21: error: redeclaration of ‘int n’
    5 |         int n,a,b,c,n;
      |                     ^
foo.cc:5:13: note: ‘int n’ previously declared here
    5 |         int n,a,b,c,n;
      |             ^
foo.cc:10:17: error: ‘m’ was not declared in this scope
   10 |                 m=a+b;
      |                 ^