foo.cc: In function ‘int main()’:
foo.cc:7:14: warning: ‘m’ is used uninitialized [-Wuninitialized]
    7 |         for(i=m;i<=n;++i)
      |             ~^~
foo.cc:5:23: note: ‘m’ was declared here
    5 |         int i,a,s=0,j,m,n,b;
      |                       ^
foo.cc:7:18: warning: ‘n’ is used uninitialized [-Wuninitialized]
    7 |         for(i=m;i<=n;++i)
      |                 ~^~~
foo.cc:5:25: note: ‘n’ was declared here
    5 |         int i,a,s=0,j,m,n,b;
      |                         ^