View Compilation Error

0_0_25020239_1738.cpp: In function 'int main()':
0_0_25020239_1738.cpp:22:17: error: 'strlen' was not declared in this scope
   len1=strlen(s2);
                 ^
0_0_25020239_1738.cpp:24:25: error: 'memset' was not declared in this scope
   memset(dp,0,sizeof(dp));
                         ^