View Compilation Error

0_0_38588721_17140.cpp: In function 'int main()':
0_0_38588721_17140.cpp:66:12: error: 'sqrt' was not declared in this scope
         sz=sqrt(2*mm);
            ^~~~
0_0_38588721_17140.cpp:66:12: note: suggested alternative: 'stat'
         sz=sqrt(2*mm);
            ^~~~
            stat