#include<stdio.h>
#include<string.h>

#define minim(a,b) (a<b ? a : b)
#define NMAX 606
#define INF 1000000006

int n,m,rez[NMAX][NMAX];
char ch[205];
int f[NMAX][4],sol[NMAX];
char s[NMAX];

int main ()
{
    int i,j,t,ind,mod;
    int gr,a,b,val,k;
    
    freopen("perb.in","r",stdin);
    freopen("perb.out","w",stdout);
    scanf("%d%d\n",&n,&m);
    scanf("%s",s+1);
    ch['C']=1;
    ch['G']=2;
    ch['T']=3;
    for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++)
            rez[i][j]=INF;
    for(i=1;i<=n;i++)
        for(j=1;j<=(n-i+1)/2;j++)
        {
            if(j==1)
                mod=0;
            else
                mod=1;
            for(t=0;t<j;t++)
            {
                memset(f[t],0,sizeof(f[t]));
                sol[t]=0;
            }
            for(t=i;t<=n;t++)
            {
                ind=ch[(int)s[t]];
                f[mod][ind]++;
                if(f[mod][ind]>sol[mod])
                    sol[mod]=f[mod][ind];
                if(!mod && t!=i+j-1)
                {
                    gr=(t-i+1)/j;
                    val=0;
                    for(k=0;k<j;k++)
                        val+=gr-sol[k];
                    rez[i][t]=minim(rez[i][t],val);
                }
                mod++;
                if(mod==j)
                    mod=0;
            }
        }
    for(i=1;i<=m;i++)
    {
        scanf("%d%d",&a,&b);
        printf("%d\n",rez[a][b]);
    }
    
    return 0;
}