View Compilation Error

0_0_33987020_21016.cpp: In function 'void calc(int, int, int)':
0_0_33987020_21016.cpp:76:16: error: 'NTT_pre' was not declared in this scope
     NTT_pre(len); NTT(u,len,1); NTT(v,len,1);
                ^