Alternative to goto in c# -

i given program employer, , asked find out wrong it. have heard bad things goto's, , not have experience them whatsoever. know how reprogram without goto's? absolute mess...

class goto { public int solve(int limit) { int result = 1; list num = new list(); list usedprimes = new list();

        alpha:         int = 2;          if (isprime(i)) { num.add(i); }         i++;         if (i <= limit) goto alpha;          result = 1;           beta:         if (num.count == 0) goto gamma;         int upper, value;         int prime = num[0];         //system.out.println(prime);         upper = (limit - 1) / prime;         value = upper * prime;         if (!(isprime(upper) && upper != 1)) goto epsilon;          //addusedprime(upper, usedprimes);         deletefromlist(upper, num);         goto phi;         epsilon:         deletefromlist(prime, num);         phi:         if (checkfactors(value, usedprimes)) goto zeta;         result += value;         console.writeline(prime + ", " + upper + ", " + value + ", " + result);          addusedprime(prime, usedprimes);          (int j = 2; j <= value; j++)         {             if ((value % j == 0) && isprime(j))             {                 //system.out.println("adding used prime: " + j);                 addusedprime(j, usedprimes);             }         }         goto iota;         zeta:         if (!checkfactors(prime, usedprimes))         {              result += prime;             addusedprime(prime, usedprimes);             console.writeline(prime + ", " + upper + ", " + value + ", " + result + "   (grace)");             deletefromlist(prime, num);         }         iota:         goto beta;         gamma:         return result;     }     private void deletefromlist(int prime, list<int> num)     {         (int = 0; < num.count; i++)         {             if (prime == num[i])             {                 num.remove(i);                 break;             }         }     }     private void addusedprime(int prime, list<int> usedprimes)     {         int i;         = 0;         alpha:         if (prime == usedprimes[i]) { goto gamma; }         i++;         if (i < usedprimes.count) goto alpha;         gamma:         if (i == usedprimes.count) { usedprimes.add(prime); }     }     private boolean checkfactors(int num, list<int> primes)     {         boolean result = false;         int = 0;         epsilon:          if (num % primes[i] == 0) { result = true; goto delta; }         i++;         if (i < primes.count) goto epsilon;         delta:         return result;     }     private boolean isprime(int num)     {         boolean result = true;         if (num == 2 || num == 1) return true;         int limit = (int)math.sqrt(num);         int = 2;         epsilon:         if (num % == 0) { result = false; goto delta;}         i++;         if (i <= limit) goto epsilon;         delta:         return result;     } }