View Compilation Error

0_0_19232416_12833.cpp: In function 'int main()':
0_0_19232416_12833.cpp:9:21: error: 'arr' was not declared in this scope
             x[i]=(a*arr[i-1]+b*arr[i-2])%7;
                     ^
0_0_19232416_12833.cpp:10:23: error: 'arr' was not declared in this scope
         printf("%d\n",arr[n%48?n%48:48]);
                       ^