Main.cc: In function ‘int main()’:
Main.cc:5:10: error: ‘M’ was not declared in this scope
cin>>n>>M>>x>>y;
^
Main.cc:9:3: error: ‘col’ was not declared in this scope
col[a]++;
^~~
Main.cc:9:3: note: suggested alternative: ‘atol’
col[a]++;
^~~
atol
Main.cc:14:3: error: ‘row’ was not declared in this scope
row[a]++;
^~~