import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum INF = 10L^^18;

void main() {
  try {
    for (; ; ) {
      const H = readInt;
      const W = readInt;
      auto A = new long[][](H, W);
      foreach (x; 0 .. H) foreach (y; 0 .. W) {
        A[x][y] = readLong;
      }
      
      auto dp = new long[W];
      auto DP = new long[H];
      dp[] = INF;
      DP[] = INF;
      DP[0] = 0;
      foreach (x; 0 .. H) {
        foreach (y; 0 .. W) dp[y] += A[x][y];
        foreach (y; 0 .. W) chmin(DP[x], dp[y]);
        foreach (y; 0 .. W) chmin(dp[y], DP[x] + A[x][y]);
        debug {
          writeln(x, " ", dp);
        }
      }
      debug {
        writeln(DP);
      }
      writeln(DP[H - 1]);
    }
  } catch (EOFException e) {
  }
}