View Compilation Error

0_0_32922347_20070.cpp: In function 'int main()':
0_0_32922347_20070.cpp:56:54: error: 'a3' was not declared in this scope
    printf("%d\n",min(sum[gs]+y[0],max(max(a1,a2),max(a3,a4))));
                                                      ^