View Compilation Error

0_0_25916405_23153.cpp: In function 'int main()':
0_0_25916405_23153.cpp:49:14: error: 'N2' was not declared in this scope
         cin>>N2;
              ^
0_0_25916405_23153.cpp:57:14: error: 'N3' was not declared in this scope
         cin>>N3;
              ^
0_0_25916405_23153.cpp:74:14: error: 'N4' was not declared in this scope
         cin>>N4;
              ^