View Compilation Error

0_0_38557124_6501.cpp:6:51: error: 'N' was not declared in this scope
 int a[maxn],bug[maxn],dp[maxn][maxn],b[maxn], stp[N];
                                                   ^
0_0_38557124_6501.cpp: In function 'void rua()':
0_0_38557124_6501.cpp:31:12: error: 'st' was not declared in this scope
     memset(st,0,sizeof st);
            ^