#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxN 602
using namespace std;
int n, m, l, k, x, y, i, j, v[maxN], dp[maxN][maxN], a[maxN][maxN], app[maxN][4];
char s[maxN];
void read()
{
    freopen("perb.in", "r", stdin);
    scanf("%d %d\n", &n, &m);
    gets(s + 1);
    for (i = 1; i <= n; ++ i)
    {
        if (s[i] == 'A')
            v[i] = 0;
        else if (s[i] == 'C')
            v[i] = 1;
        else if (s[i] == 'G')
            v[i] = 2;
        else
            v[i] = 3;
    }
}
void solve()
{
    int nr;
    for (i = 1; i <= n; ++ i)
        for (j = i; j <= n; ++ j)
            dp[i][j] = j - i;

    for (l = 1; l * 2 <= n; ++ l)
        for (i = 1; i + 2 * l - 1 <= n; ++ i)
        {
            j = i + l - 1;
            a[i][j] = 0;
            for(k = i; k < j + l; ++ k)
            {
                memset(app[k - i], 0, sizeof(app[k - i]));
                app[k - i][v[k]] = 1;
            }
            nr = 1;
            for(j = i + 2 * l - 1; j <= n; j += l)
            {
                ++ nr;
                a[i][j] = 0;
                for(k = 0; k < l; ++ k)
                {
                    ++ app[k][v[j - l + 1 + k]];
                    a[i][j] += nr - max(max(app[k][0], app[k][1]), max(app[k][2], app[k][3]));
                }
                if(a[i][j] < dp[i][j])
                    dp[i][j] = a[i][j];
            }
        }
}
void write()
{
    freopen("perb.out", "w", stdout);
    while (m --)
    {
        scanf("%d %d", &x, &y);
        printf("%d\n", dp[x][y]);
    }
}
int main()
{
    read();
    solve();
    write();
    return 0;
}