/in/foo.cc: In function 'int main()':
/in/foo.cc:24:23: error: expected ')' before ']' token
        if(f[j+a[i]]==0]){
                       ^
/in/foo.cc:24:23: error: expected primary-expression before ']' token
/in/foo.cc:23:9: warning: suggest explicit braces to avoid ambiguous 'else' [-Wparentheses]
       if(f[j]>0)
         ^