package main

import (
  "bufio"
  "os"
  "strconv"
  "strings"
  "fmt"
)

var reader = bufio.NewReaderSize(os.Stdin, 1000000)
var writer = bufio.NewWriter(os.Stdout)
func NextLine() string {
  buffer := make([]byte, 0)
  for true {
    line, isPrefix, err := reader.ReadLine()
    if err != nil { panic(err) }
    buffer = append(buffer, line...)
    if !isPrefix { break }
  }
  return string(buffer)
}
func NextInt() int {
  n, _ := strconv.Atoi(NextLine())
  return n
}
func NextIntVec() []int {
  L := strings.Split(NextLine(), " ")
  N := make([]int, len(L))
  for i := range N {
    N[i], _ = strconv.Atoi(L[i])
  }
  return N
}
func NextFloat() float64 {
  n, _ := strconv.ParseFloat(NextLine(), 64)
  return n
}
func NextFloatVec() []float64 {
  L := strings.Split(NextLine(), " ")
  N := make([]float64, len(L))
  for i := range N {
    N[i], _ = strconv.ParseFloat(L[i], 64)
  }
  return N
}
func Write(s interface{}) {
  fmt.Fprintln(writer, s)
}
func WriteIntVec(A []int) {
  S := make([]string, len(A))
  for i, a := range A {
    S[i] = strconv.Itoa(a)
  }
  Write(strings.Join(S, " "))
}
func Output() {
  _ = writer.Flush()
}

func MaxInt(A ...int) int {
  max := A[0]
  for _, a := range A {
    if max < a { max = a }
  }
  return max
}
func MinInt(A ...int16) int16 {
  min := A[0]
  for _, a := range A {
    if a < min { min = a }
  }
  return min
}

type Graph struct {
  Capacity [][]int16
  AdjList [][]int16
}

func (G *Graph) FordFulkerson(s, t int) int16 {
  N := len((*G).Capacity)
  P := make([]int, N)
  Q := make([]int, 0)
  for {
    for i := range P {
      P[i] = -1
    }
    P[s] = s
    Q = append(Q, s)
    for 0 < len(Q) {
      q := Q[0]
      Q = Q[1:]
      for _, adj := range (*G).AdjList[q] {
        if 0 <= P[adj] || (*G).Capacity[q][adj] <= 0 { continue }
        P[adj] = q
        Q = append(Q, int(adj))
      }
    }
    if P[t] < 0 { break }
    Dst := t
    Src := P[t]
    C := (*G).Capacity[Src][Dst]
    for Src != s {
      Dst = Src
      Src = P[Src]
      C = MinInt((*G).Capacity[Src][Dst], C)
    }
    Dst = t
    Src = P[t]
    for Dst != s {
      (*G).Capacity[Src][Dst] -= C
      (*G).Capacity[Dst][Src] += C
      Dst = Src
      Src = P[Src]
    }
  }
  F := int16(0)
  for _, Cap := range (*G).Capacity {
    F += Cap[s]
  }
  return F
}

const Inf = 16383

func Solve() {
  HW := NextIntVec()
  H, W := HW[0], HW[1]
  E := make([][]int16, H * W + H + W)
  for i := range E {
    E[i] = make([]int16, H * W + H + W)
  }
  Adj := make([][]int16, H * W + H + W)
  for i := range Adj {
    Adj[i] = make([]int16, 0)
  }
  s, t := 0, 0
  for i := 0; i < H; i++ {
    A := NextLine()
    for j, a := range A {
      p := i * W + j
      switch a {
      case 'S':
        E[p][H * W + i] = Inf
        E[p][H * W + H + j] = Inf
        s = p
        Adj[p] = append(Adj[p], int16(H * W + i))
        Adj[p] = append(Adj[p], int16(H * W + H + j))
      case 'T':
        E[H * W + i][p] = Inf
        E[H * W + H + j][p] = Inf
        t = p
        Adj[H * W + i] = append(Adj[H * W + i], int16(p))
        Adj[H * W + H + j] = append(Adj[H * W + H + j], int16(p))
      case 'o':
        E[p][H * W + i] = 1
        E[H * W + i][p] = 1
        E[p][H * W + H + j] = 1
        E[H * W + H + j][p] = 1
        Adj[p] = append(Adj[p], int16(H * W + i))
        Adj[p] = append(Adj[p], int16(H * W + H + j))
        Adj[H * W + i] = append(Adj[H * W + i], int16(p))
        Adj[H * W + H + j] = append(Adj[H * W + H + j], int16(p))
      }
    }
  }
  G := Graph{E, Adj}
  ans := G.FordFulkerson(s, t)
  if Inf <= ans { ans = -1 }
  Write(ans)
  return
}

func main() {
  Solve()
  Output()
}

Measured memory_bytes: 153472