View Compilation Error

0_0_14132500_13452.cpp: In function 'int main()':
0_0_14132500_13452.cpp:6:18: error: 'n' was not declared in this scope
     while(cin >> n >> m >> x >> y){       
                  ^
0_0_14132500_13452.cpp:6:23: error: 'm' was not declared in this scope
     while(cin >> n >> m >> x >> y){       
                       ^
0_0_14132500_13452.cpp:6:28: error: 'x' was not declared in this scope
     while(cin >> n >> m >> x >> y){       
                            ^
0_0_14132500_13452.cpp:6:33: error: 'y' was not declared in this scope
     while(cin >> n >> m >> x >> y){       
                                 ^