View Compilation Error

In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/cassert:43:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/x86_64-w64-mingw32/bits/stdc++.h:33,
                 from 0_0_26320882_10424.cpp:2:
0_0_26320882_10424.cpp: In function 'void update(int, int, int, int, int)':
0_0_26320882_10424.cpp:34:9: error: 'y1' was not declared in this scope
  assert(y1<=y2);
         ^
0_0_26320882_10424.cpp:34:13: error: 'y2' was not declared in this scope
  assert(y1<=y2);
             ^