View Compilation Error

0_0_37695273_18227.cpp: In function 'int main()':
0_0_37695273_18227.cpp:56:11: error: 'x1' was not declared in this scope
    cin >> x1 >> y1 >> x2 >> y2;
           ^
0_0_37695273_18227.cpp:56:17: error: 'y1' was not declared in this scope
    cin >> x1 >> y1 >> x2 >> y2;
                 ^
0_0_37695273_18227.cpp:56:23: error: 'x2' was not declared in this scope
    cin >> x1 >> y1 >> x2 >> y2;
                       ^
0_0_37695273_18227.cpp:56:29: error: 'y2' was not declared in this scope
    cin >> x1 >> y1 >> x2 >> y2;
                             ^
0_0_37695273_18227.cpp:57:27: error: expected primary-expression before ')' token
    if(b[x2][y2]-b[x1][y1]<)
                           ^
0_0_37695273_18227.cpp:58:3: error: expected primary-expression before '}' token
   }
   ^