foo.cpp: In function 'int main(int, char**)':
foo.cpp:16:10: error: expected primary-expression before 'int'
     cin>>int n;
          ^
foo.cpp:16:10: error: expected ';' before 'int'
foo.cpp:19:30: error: 'n' was not declared in this scope
       if(a[i]+a[j]+a[i+j]+4==n) 
                              ^