View Compilation Error

0_0_17266113_29679.cpp:17:5: error: conflicting declaration 'int N'
 int N,M,C,P[M],vis[maxn+5];
     ^
0_0_17266113_29679.cpp:15:11: note: previous declaration as 'const int N'
 const int N = 5*1e8;
           ^
0_0_17266113_29679.cpp:17:7: error: conflicting declaration 'int M'
 int N,M,C,P[M],vis[maxn+5];
       ^
0_0_17266113_29679.cpp:16:11: note: previous declaration as 'const int M'
 const int M = 3*1e4;
           ^