View Compilation Error

0_0_29950776_31952.cpp: In function 'int main()':
0_0_29950776_31952.cpp:23:22: error: 'strlen' was not declared in this scope
   int lena=strlen(a+1)-1, lenb=strlen(b+1)-1;
                      ^
0_0_29950776_31952.cpp:25:19: error: 'lenb' was not declared in this scope
   for(int i=1; i<=lenb; i++)
                   ^
0_0_29950776_31952.cpp:54:9: error: 'lenb' was not declared in this scope
   if(dp[lenb][lena]) printf("yes\n");
         ^