#include<cstdio>
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 getMiscari(int st, int fn, int pas) {
	int ct[5];
	int i, j, _max, rsp = 0;
	for(i = 0; i < pas; ++i) {
		_max = 0;
		for(j = 1; j <= 4; ++j)
			ct[j] = 0;
			
		for(j = st + i; j <= fn; j += pas) 
			++ct[v[j]];
		for(j = 1; j <= 4; ++j)
			if(ct[j] > _max)
				_max = ct[j];
				
		rsp += (fn - st + 1) / pas - _max; 
	}
	return rsp;	
}

int main() {
	int i, j, st, fn, _min, ax, t, k, relem, elem;
	char c; 
	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(i = 1; i <= n; ++i)
		for(j = i; j <= n; ++j)
			rsp[i][j] = -1;
	for(; m; --m) {
		scanf("%d%d", &i, &j);
		if(rsp[i][j] == -1) {
			relem = elem;
			elem = (j - i + 1);
				_min = getMiscari(i, j, 1);
				for(k = 0; prim[k] * prim[k] <= relem; ++k)
					if(relem % prim[k] == 0) {
						if( (ax = getMiscari(i, j, elem / prim[k])) < _min )
							_min = ax;
						while(relem % prim[k] == 0)
							relem /= prim[k];
					}
				if(relem != 1)
					if( (ax = getMiscari(i, j, elem / relem)) < _min )
						_min = ax;
				rsp[i][j] = _min;
		}
		printf("%d\n", rsp[i][j]);
	}
	return 0;
}