View Compilation Error

0_0_36689598_13525.cpp: In function 'int main()':
0_0_36689598_13525.cpp:17:3: error: 'arr' was not declared in this scope
   arr[i] = (a*arr[i - 1] + b*arr[i - 2]) % 7; 
   ^
0_0_36689598_13525.cpp:21:10: error: 'arr' was not declared in this scope
   return arr[n % 49];
          ^
0_0_36689598_13525.cpp:23:10: error: 'arr' was not declared in this scope
   return arr[1];
          ^
0_0_36689598_13525.cpp:24:1: error: expected '}' at end of input
 }
 ^