View Compilation Error

0_0_38674253_15610.cpp: In function 'int main()':
0_0_38674253_15610.cpp:55:68: error: 'cou' was not declared in this scope; did you mean 'cos'?
   55 |         if(a.substr(mark[x], m).compare(b.substr(mark[y], m)) != 0)cou<<"No\n";
      |                                                                    ^~~
      |                                                                    cos