View Compilation Error

0_0_20889557_7199.cpp: In function 'void insrt(int, int, int)':
0_0_20889557_7199.cpp:40:41: error: 'memset' was not declared in this scope
         memset(ch[tot],0,sizeof(ch[tot]));
                                         ^
0_0_20889557_7199.cpp: In function 'void dfs(int, int)':
0_0_20889557_7199.cpp:51:37: error: 'memset' was not declared in this scope
     memset(ch[tot],0,sizeof(ch[tot]));
                                     ^
0_0_20889557_7199.cpp: In function 'int main()':
0_0_20889557_7199.cpp:129:29: error: 'memset' was not declared in this scope
         memset(f,0,sizeof(f));
                             ^