G.java

import java.io.IOException;
import java.io.InputStream;

public class G {
    public static void main(String[] args) throws Exception {
        FastScanner fs = new FastScanner(System.in);
        Integer nObj = fs.nextIntNullable();
        Integer mObj = fs.nextIntNullable();
        if (nObj == null || mObj == null) {
            System.out.println(-1);
            return;
        }
        int n = nObj, m = mObj;

        int[][] state = new int[n][m];
        for (int i = 0; i < n; i++) {
            String line = fs.nextTokenLineTrimmed();
            while (line.length() < m) {
                String extra = fs.nextTokenLineTrimmed();
                line += extra;
            }
            for (int j = 0; j < m; j++) {
                char c = line.charAt(j);
                if (c == 'S') state[i][j] = 1;
                else if (c == 'K') state[i][j] = 0;
                else {
                    System.out.println(-1);
                    return;
                }
            }
        }

        int best = Integer.MAX_VALUE;

        for (int r0 = 0; r0 <= 1; r0++) {
            int[] R = new int[n];
            int[] C = new int[m];

            for (int j = 0; j < m; j++) {
                C[j] = state[0][j] ^ r0;
            }
            for (int i = 0; i < n; i++) {
                R[i] = state[i][0] ^ C[0];
            }

            boolean ok = true;
            outer:
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < m; j++) {
                    if ((R[i] ^ C[j]) != state[i][j]) {
                        ok = false;
                        break outer;
                    }
                }
            }

            if (ok) {
                int steps = 0;
                for (int x : R) steps += x;
                for (int x : C) steps += x;
                best = Math.min(best, steps);
            }
        }

        System.out.println(best == Integer.MAX_VALUE ? -1 : best);
    }

    static class FastScanner {
        private final InputStream in;
        private final byte[] buffer = new byte[1 << 16];
        private int ptr = 0, len = 0;
        FastScanner(InputStream is) { in = is; }

        private int read() throws IOException {
            if (ptr >= len) {
                len = in.read(buffer);
                ptr = 0;
                if (len <= 0) return -1;
            }
            return buffer[ptr++];
        }

        Integer nextIntNullable() throws IOException {
            int c;
            do {
                c = read();
                if (c == -1) return null;
            } while (c <= ' ');
            int sgn = 1;
            if (c == '-') { sgn = -1; c = read(); }
            int val = 0;
            while (c > ' ') {
                val = val * 10 + (c - '0');
                c = read();
            }
            return val * sgn;
        }

        String nextTokenLineTrimmed() throws IOException {
            StringBuilder sb = new StringBuilder();
            int c;
            while (true) {
                c = read();
                if (c == -1 || c == '\n' || c == '\r') break;
                if (c != ' ') sb.append((char) c);
            }
            if (c == '\r') {
                int next = read();
                if (next != '\n') ptr--;
            }
            return sb.toString().trim();
        }
    }
}