View Compilation Error

0_0_21964949_1476.cpp: In function 'int main()':
0_0_21964949_1476.cpp:105:31: error: 'a' was not declared in this scope
             scanf("%d%d%d%d",&a,&b,&c,&d);
                               ^
0_0_21964949_1476.cpp:105:34: error: 'b' was not declared in this scope
             scanf("%d%d%d%d",&a,&b,&c,&d);
                                  ^
0_0_21964949_1476.cpp:105:37: error: 'c' was not declared in this scope
             scanf("%d%d%d%d",&a,&b,&c,&d);
                                     ^
0_0_21964949_1476.cpp:105:40: error: 'd' was not declared in this scope
             scanf("%d%d%d%d",&a,&b,&c,&d);
                                        ^