#include <stdio.h>

int main () {
  int n = 0;
  int m = 0;
  long long a[1000][1000] = {};

  int res = 0;
  
  long long dp[1000][1000] = {};
  long long ans = 0LL;
  
  res = scanf("%d", &n);
  res = scanf("%d", &m);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      res = scanf("%lld", a[i]+j);
    }
  }
  
  if (n <= 1) {
    printf("0\n");
    return 0;
  }
  
  for (int i = 0; i < m; i++) {
    dp[0][i] = a[0][i];
  }
  
  for (int i = 1; i < n; i++) {
    long long min = dp[i-1][0];
    for (int j = 1; j < m; j++) {
      if (dp[i-1][j] < min) {
        min = dp[i-1][j];
      }
    }
    for (int j = 0; j < m; j++) {
      dp[i][j] = dp[i-1][j]+a[i][j];
      if (min+a[i][j]+a[i-1][j] < dp[i][j]) {
        dp[i][j] = min+a[i][j]+a[i-1][j];
      }
    }
  }
  
  ans = dp[n-1][0];
  for (int i = 1; i < m; i++) {
    if (dp[n-1][i] < ans) {
      ans = dp[n-1][i];
    }
  }
  
  printf("%lld\n", ans);
  return 0;
}