max(a,b){return a>b?a:b;}
min(a,b){return a<b?a:b;}
P[]={
    2,    3,    5,    7,   11,   13,   17,   19,   23,   29,   31,   37,   41,
   43,   47,   53,   59,   61,   67,   71,   73,   79,   83,   89,   97,  101,
  103,  107,  109,  113,  127,  131,  137,  139,  149,  151,  157,  163,  167,
  173,  179,  181,  191,  193,  197,  199,  211,  223,  227,  229,  233,  239,
  241,  251,  257,  263,  269,  271,  277,  281,  283,  293,  307,  311,  313,
  317,  331,  337,  347,  349,  353,  359,  367,  373,  379,  383,  389,  397,
  401,  409,  419,  421,  431,  433,  439,  443,  449,  457,  461,  463,  467,
  479,  487,  491,  499,  503,  509,  521,  523,  541,  547,  557,  563,  569,
  571,  577,  587,  593,  599,  601,  607,  613,  617,  619,  631,  641,  643,
  647,  653,  659,  661,  673,  677,  683,  691,  701,  709,  719,  727,  733,
  739,  743,  751,  757,  761,  769,  773,  787,  797,  809,  811,  821,  823,
  827,  829,  839,  853,  857,  859,  863,  877,  881,  883,  887,  907,  911,
  919,  929,  937,  941,  947,  953,  967,  971,  977,  983,  991,  997, 1009,
 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091,
 1093, 1097, 1103, 1109, 1117, 1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187,
 1193, 1201, 1213, 1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283,
 1289, 1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373, 1381,
 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453, 1459, 1471, 1481,
 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531, 1543, 1549, 1553, 1559, 1567,
 1571, 1579, 1583, 1597, 1601, 1607, 1609, 1613, 1619, 1621, 1627, 1637, 1657,
 1663, 1667, 1669, 1693, 1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753,
 1759, 1777, 1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871,
 1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951, 1973, 1979,
 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029, 2039, 2053, 2063, 2069,
 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2129, 2131, 2137, 2141, 2143, 2153,
 2161, 2179, 2203, 2207, 2213, 2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273,
 2281, 2287, 2293, 2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, 2371,
 2377, 2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437, 2441, 2447, 2459,
 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551, 2557, 2579, 2591,
 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659, 2663, 2671, 2677, 2683, 2687,
 2689, 2693, 2699, 2707, 2711, 2713, 2719, 2729, 2731, 2741, 2749, 2753, 2767,
 2777, 2789, 2791, 2797, 2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861,
 2879, 2887, 2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971,
 2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079, 3083, 3089,
 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187, 3191, 3203, 3209, 3217,
 3221, 3229, 3251, 3253, 3257, 3259, 3271, 3299, 3301, 3307, 3313, 3319, 3323,
 3329, 3331, 3343, 3347, 3359, 3361, 3371, 3373, 3389, 3391, 3407, 3413, 3433,
 3449, 3457, 3461, 3463, 3467, 3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533,
 3539, 3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607, 3613, 3617, 3623,
 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701, 3709, 3719, 3727,
 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797, 3803, 3821, 3823, 3833, 3847,
 3851, 3853, 3863, 3877, 3881, 3889, 3907, 3911, 3917, 3919, 3923, 3929, 3931,
 3943, 3947, 3967, 3989, 4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051,
 4057, 4073, 4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157,
 4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253, 4259, 4261,
 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349, 4357, 4363, 4373, 4391,
 4397, 4409, 4421, 4423, 4441, 4447, 4451, 4457, 4463, 4481, 4483, 4493, 4507,
 4513, 4517, 4519, 4523, 4547, 4549, 4561, 4567, 4583, 4591, 4597, 4603, 4621,
 4637, 4639, 4643, 4649, 4651, 4657, 4663, 4673, 4679, 4691, 4703, 4721, 4723,
 4729, 4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817, 4831,
 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937, 4943, 4951, 4957,
 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009, 5011, 5021, 5023, 5039, 5051,
 5059, 5077, 5081, 5087, 5099, 5101, 5107, 5113, 5119, 5147, 5153, 5167, 5171,
 5179, 5189, 5197, 5209, 5227, 5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297,
 5303, 5309, 5323, 5333, 5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417,
 5419, 5431, 5437, 5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501, 5503, 5507,
 5519, 5521, 5527, 5531, 5557, 5563, 5569, 5573, 5581, 5591, 5623, 5639, 5641,
 5647, 5651, 5653, 5657, 5659, 5669, 5683, 5689, 5693, 5701, 5711, 5717, 5737,
 5741, 5743, 5749, 5779, 5783, 5791, 5801, 5807, 5813, 5821, 5827, 5839, 5843,
 5849, 5851, 5857, 5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939,
 5953, 5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, 6067, 6073, 6079,
 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151, 6163, 6173, 6197, 6199,
 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263, 6269, 6271, 6277, 6287, 6299,
 6301, 6311, 6317, 6323, 6329, 6337, 6343, 6353, 6359, 6361, 6367, 6373, 6379,
 6389, 6397, 6421, 6427, 6449, 6451, 6469, 6473, 6481, 6491, 6521, 6529, 6547,
 6551, 6553, 6563, 6569, 6571, 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659,
 6661, 6673, 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737, 6761, 6763,
 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833, 6841, 6857, 6863, 6869,
 6871, 6883, 6899, 6907, 6911, 6917, 6947, 6949, 6959, 6961, 6967, 6971, 6977,
 6983, 6991, 6997, 7001, 7013, 7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103,
 7109, 7121, 7127, 7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219,
 7229, 7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333, 7349,
 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477, 7481, 7487, 7489,
 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547, 7549, 7559, 7561, 7573, 7577,
 7583, 7589, 7591, 7603, 7607, 7621, 7639, 7643, 7649, 7669, 7673, 7681, 7687,
 7691, 7699, 7703, 7717, 7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817,
 7823, 7829, 7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927,
 7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, 8039, 8053, 8059, 8069,
 8081, 8087, 8089, 8093, 8101, 8111, 8117, 8123, 8147, 8161, 8167, 8171, 8179,
 8191, 8209, 8219, 8221, 8231, 8233, 8237, 8243, 8263, 8269, 8273, 8287, 8291,
 8293, 8297, 8311, 8317, 8329, 8353, 8363, 8369, 8377, 8387, 8389, 8419, 8423,
 8429, 8431, 8443, 8447, 8461, 8467, 8501, 8513, 8521, 8527, 8537, 8539, 8543,
 8563, 8573, 8581, 8597, 8599, 8609, 8623, 8627, 8629, 8641, 8647, 8663, 8669,
 8677, 8681, 8689, 8693, 8699, 8707, 8713, 8719, 8731, 8737, 8741, 8747, 8753,
 8761, 8779, 8783, 8803, 8807, 8819, 8821, 8831, 8837, 8839, 8849, 8861, 8863,
 8867, 8887, 8893, 8923, 8929, 8933, 8941, 8951, 8963, 8969, 8971, 8999, 9001,
 9007, 9011, 9013, 9029, 9041, 9043, 9049, 9059, 9067, 9091, 9103, 9109, 9127,
 9133, 9137, 9151, 9157, 9161, 9173, 9181, 9187, 9199, 9203, 9209, 9221, 9227,
 9239, 9241, 9257, 9277, 9281, 9283, 9293, 9311, 9319, 9323, 9337, 9341, 9343,
 9349, 9371, 9377, 9391, 9397, 9403, 9413, 9419, 9421, 9431, 9433, 9437, 9439,
 9461, 9463, 9467, 9473, 9479, 9491, 9497, 9511, 9521, 9533, 9539, 9547, 9551,
 9587, 9601, 9613, 9619, 9623, 9629, 9631, 9643, 9649, 9661, 9677, 9679, 9689,
 9697, 9719, 9721, 9733, 9739, 9743, 9749, 9767, 9769, 9781, 9787, 9791, 9803,
 9811, 9817, 9829, 9833, 9839, 9851, 9857, 9859, 9871, 9883, 9887, 9901, 9907,
 9923, 9929, 9931, 9941, 9949, 9967, 9973,10007,10009,10037,10039,10061,10067,
10069,10079,10091,10093,10099,10103,10111,10133,10139,10141,10151,10159,10163,
10169,10177,10181,10193,10211,10223,10243,10247,10253,10259,10267,10271,10273,
10289,10301,10303,10313,10321,10331,10333,10337,10343,10357,10369,10391,10399,
10427,10429,10433,10453,10457,10459,10463,10477,10487,10499,10501,10513,10529,
10531,10559,10567,10589,10597,10601,10607,10613,10627,10631,10639,10651,10657,
10663,10667,10687,10691,10709,10711,10723,10729,10733,10739,10753,10771,10781,
10789,10799,10831,10837,10847,10853,10859,10861,10867,10883,10889,10891,10903,
10909,10937,10939,10949,10957,10973,10979,10987,10993,11003,11027,11047,11057,
11059,11069,11071,11083,11087,11093,11113,11117,11119,11131,11149,11159,11161,
11171,11173,11177,11197,11213,11239,11243,11251,11257,11261,11273,11279,11287,
11299,11311,11317,11321,11329,11351,11353,11369,11383,11393,11399,11411,11423,
11437,11443,11447,11467,11471,11483,11489,11491,11497,11503,11519,11527,11549,
11551,11579,11587,11593,11597,11617,11621,11633,11657,11677,11681,11689,11699,
11701,11717,11719,11731,11743,11777,11779,11783,11789,11801,11807,11813,11821,
11827,11831,11833,11839,11863,11867,11887,11897,11903,11909,11923,11927,11933,
11939,11941,11953,11959,11969,11971,11981,11987,12007,12011,12037,12041,12043,
12049,12071,12073,12097,12101,12107,12109,12113,12119,12143,12149,12157,12161,
12163,12197,12203,12211,12227,12239,12241,12251,12253,12263,12269,12277,12281,
12289,12301,12323,12329,12343,12347,12373,12377,12379,12391,12401,12409,12413,
12421,12433,12437,12451,12457,12473,12479,12487,12491,12497,12503,12511,12517,
12527,12539,12541,12547,12553,12569,12577,12583,12589,12601,12611,12613,12619,
12637,12641,12647,12653,12659,12671,12689,12697,12703,12713,12721,12739,12743,
12757,12763,12781,12791,12799,12809,12821,12823,12829,12841,12853,12889,12893,
12899,12907,12911,12917,12919,12923,12941,12953,12959,12967,12973,12979,12983,
13001,13003,13007,13009,13033,13037,13043,13049,13063,13093,13099,13103,13109,
13121,13127,13147,13151,13159,13163,13171,13177,13183,13187,13217,13219,13229,
13241,13249,13259,13267,13291,13297,13309,13313,13327,13331,13337,13339,13367,
13381,13397,13399,13411,13417,13421,13441,13451,13457,13463,13469,13477,13487,
13499,13513,13523,13537,13553,13567,13577,13591,13597,13613,13619,13627,13633,
13649,13669,13679,13681,13687,13691,13693,13697,13709,13711,13721,13723,13729,
13751,13757,13759,13763,13781,13789,13799,13807,13829,13831,13841,13859,13873,
13877,13879,13883,13901,13903,13907,13913,13921,13931,13933,13963,13967,13997,
13999,14009,14011,14029,14033,14051,14057,14071,14081,14083,14087,14107,14143,
14149,14153,14159,14173,14177,14197,14207,14221,14243,14249,14251,14281,14293,
14303,14321,14323,14327,14341,14347,14369,14387,14389,14401,14407,14411,14419,
14423,14431,14437,14447,14449,14461,14479,14489,14503,14519,14533,14537,14543,
14549,14551,14557,14561,14563,14591,14593,14621,14627,14629,14633,14639,14653,
14657,14669,14683,14699,14713,14717,14723,14731,14737,14741,14747,14753,14759,
14767,14771,14779,14783,14797,14813,14821,14827,14831,14843,14851,14867,14869,
14879,14887,14891,14897,14923,14929,14939,14947,14951,14957,14969,14983,15013,
15017,15031,15053,15061,15073,15077,15083,15091,15101,15107,15121,15131,15137,
15139,15149,15161,15173,15187,15193,15199,15217,15227,15233,15241,15259,15263,
15269,15271,15277,15287,15289,15299,15307,15313,15319,15329,15331,15349,15359,
15361,15373,15377,15383,15391,15401,15413,15427,15439,15443,15451,15461,15467,
15473,15493,15497,15511,15527,15541,15551,15559,15569,15581,15583,15601,15607,
15619,15629,15641,15643,15647,15649,15661,15667,15671,15679,15683,15727,15731,
15733,15737,15739,15749,15761,15767,15773,15787,15791,15797,15803,15809,15817,
15823,15859,15877,15881,15887,15889,15901,15907,15913,15919,15923,15937,15959,
15971,15973,15991,16001,16007,16033,16057,16061,16063,16067,16069,16073,16087,
16091,16097,16103,16111,16127,16139,16141,16183,16187,16189,16193,16217,16223,
16229,16231,16249,16253,16267,16273,16301,16319,16333,16339,16349,16361,16363,
16369,16381,16411,16417,16421,16427,16433,16447,16451,16453,16477,16481,16487,
16493,16519,16529,16547,16553,16561,16567,16573,16603,16607,16619,16631,16633,
16649,16651,16657,16661,16673,16691,16693,16699,16703,16729,16741,16747,16759,
16763,16787,16811,16823,16829,16831,16843,16871,16879,16883,16889,16901,16903,
16921,16927,16931,16937,16943,16963,16979,16981,16987,16993,17011,17021,17027,
17029,17033,17041,17047,17053,17077,17093,17099,17107,17117,17123,17137,17159,
17167,17183,17189,17191,17203,17207,17209,17231,17239,17257,17291,17293,17299,
17317,17321,17327,17333,17341,17351,17359,17377,17383,17387,17389,17393,17401,
17417,17419,17431,17443,17449,17467,17471,17477,17483,17489,17491,17497,17509,
17519,17539,17551,17569,17573,17579,17581,17597,17599,17609,17623,17627,17657,
17659,17669,17681,17683,17707,17713,17729,17737,17747,17749,17761,17783,17789,
17791,17807,17827,17837,17839,17851,17863,17881,17891,17903,17909,17911,17921,
17923,17929,17939,17957,17959,17971,17977,17981,17987,17989,18013,18041,18043,
18047,18049,18059,18061,18077,18089,18097,18119,18121,18127,18131,18133,18143,
18149,18169,18181,18191,18199,18211,18217,18223,18229,18233,18251,18253,18257,
18269,18287,18289,18301,18307,18311,18313,18329,18341,18353,18367,18371,18379,
18397,18401,18413,18427,18433,18439,18443,18451,18457,18461,18481,18493,18503,
18517,18521,18523,18539,18541,18553,18583,18587,18593,18617,18637,18661,18671,
18679,18691,18701,18713,18719,18731,18743,18749,18757,18773,18787,18793,18797,
18803,18839,18859,18869,18899,18911,18913,18917,18919,18947,18959,18973,18979,
19001,19009,19013,19031,19037,19051,19069,19073,19079,19081,19087,19121,19139,
19141,19157,19163,19181,19183,19207,19211,19213,19219,19231,19237,19249,19259,
19267,19273,19289,19301,19309,19319,19333,19373,19379,19381,19387,19391,19403,
19417,19421,19423,19427,19429,19433,19441,19447,19457,19463,19469,19471,19477,
19483,19489,19501,19507,19531,19541,19543,19553,19559,19571,19577,19583,19597,
19603,19609,19661,19681,19687,19697,19699,19709,19717,19727,19739,19751,19753,
19759,19763,19777,19793,19801,19813,19819,19841,19843,19853,19861,19867,19889,
19891,19913,19919,19927,19937,19949,19961,19963,19973,19979,19991,19993,19997,
0};
*p=P;
N,m,i,d[20001];
main(){
	scanf("%d",&N);
	for(m=0;*p;m+=*p++){
		for(i=min(m,N-*p);i>0;--i){
			if(d[i]){
				d[i+*p]=max(d[i+*p],d[i]+1);
			}
		}
		d[*p]=d[*p]?:1;
	}
	printf("%d",d[N]?:-1);
}