View Compilation Error

0_0_25979128_24946.cpp:4:1: error: 'usingnamespace' does not name a type
 usingnamespace std;
 ^
0_0_25979128_24946.cpp: In function 'int main()':
0_0_25979128_24946.cpp:29:58: error: 'max' was not declared in this scope
                     dp[j]=max(dp[j-1]+a[j],mmax[j-1]+a[j]);
                                                          ^
0_0_25979128_24946.cpp:29:58: note: suggested alternative:
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/algorithm:62:0,
                 from 0_0_25979128_24946.cpp:2:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/stl_algo.h:3454:5: note:   'std::max'
     max(initializer_list<_Tp> __l, _Compare __comp)
     ^
0_0_25979128_24946.cpp:37:5: error: 'return0' was not declared in this scope
     return0;   
     ^