#include<cstdio>
#include<algorithm>
using namespace std;

int v[800], n, m;
const int prim[] = {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 };

int main() {
	int i, j, st, fn, _min, ax, t, k, relem, elem, pas, mmx, g, _max;
	char c; 
	int ct[5];
	int rsp[602][602];
	
	freopen("perb.in", "r", stdin);
	freopen("perb.out", "w", stdout);
	scanf("%d%d", &n, &m);
	scanf("%c", &c);
	for(i = 1; i <= n; ++i) {
		scanf("%c", &c);
		switch(c) {
			case 'A': v[i] = 1; break;
			case 'C': v[i] = 2; break;
			case 'G': v[i] = 3; break;
			case 'T': v[i] = 4; break;
		}
	}
	for(st = 1; st <= n; ++st)
		for(fn = st; fn <= n; ++fn) {
			elem = (fn - st + 1);
			_min = 1000;
			for(i = 0; prim[i] <= elem; ++i) 
				if(elem % prim[i] == 0) {
					pas = elem / prim[i];
					mmx = 0;
					for(k = 0; k < pas; ++k) {
						_max = 0;
						for(j = 1; j <= 4; ++j)
							ct[j] = 0;
						
						for(j = st + k ; j <= fn; j += pas) 
							++ct[v[j]];
						for(j = 1; j <= 4; ++j)
							if(ct[j] > _max)
								_max = ct[j];
					mmx += elem / pas - _max;
				}
				_min = min(	_min, mmx );
			}
		if(elem % elem == 0) {
					pas = elem / elem;
					for(k = 0; k < pas; ++k) {
						_max = 0; mmx = 0;
						for(j = 1; j <= 4; ++j)
							ct[j] = 0;
						
						for(j = st + k ; j <= fn; j += pas) 
							++ct[v[j]];
						for(j = 1; j <= 4; ++j)
							if(ct[j] > _max)
								_max = ct[j];
					mmx += elem / pas - _max;
				}
				_min = min(	_min, mmx );
			}
		rsp[st][fn] =  _min;
	}
			
	for(i = 1; i <= m; ++i) {
		scanf("%d%d", &st, &fn);
		printf("%d\n", rsp[st][fn]);
	}
	return 0;
}