# include <cstdio>

const char *FIN = "perb.in", *FOU = "perb.out", *adn = { "ACGT" } ;
const int MAX = 605 ;

char S[MAX] ;
int A[MAX][MAX], B[MAX][MAX] ;
int N, M ;

inline int max ( int a, int b ) {
    return (a > b ? a : b) ;
}

inline int min ( int a, int b ) {
    return (a < b ? a : b) ;
}

void solve ( int K ) {
    for ( int i = N; i ; --i ) {
        for ( int j = 0, see = i + K > N; j < 4; ++j ) {
            B[i][j] = (S[i] == adn[j]) + (see ? 0 : B[i + K][j]) ;
        }
    }

    for ( int i = 1; i <= N; ++i ) {
        for ( int j = i + 2 * K - 1; j <= N; j += K ) {
            int aux = 0;
            for ( int k = 0; k < K; ++k ) {
                int auxdf = 0 ;
                for ( int l = 0; l < 4; ++l ) {
                    auxdf = max (auxdf, B[i + k][l] - (j + k + 1 <= N ? B[j + k + 1][l] : 0)) ;
                }
                aux += (j - i + 1) / K - auxdf ;
            }
            if ( A[i][j] > aux )
                 A[i][j] = aux ;
        }
    }
}

int main (void) {
    freopen (FIN, "r", stdin) ;
    freopen (FOU, "w", stdout) ;

    scanf ( "%d %d\n", &N, &M ) ;
    fgets ( S + 1, MAX, stdin ) ;

    for ( int i = 1; i <= N; ++i ) {
        for ( int j = i + 1; j <= N; ++j ) {
            A[i][j] = 1000 ;
        }
    }

    for ( int i = 1; i <= N >> 1; ++i ) {
        solve (i) ;
    }

    for ( int i = 1, x, y; i <= M; ++i ) {
        scanf ( "%d %d", &x, &y ) ;
        printf ( "%d\n", A[x][y] ) ;
    }
}