#include<bits/stdc++.h>
#define int long long
using namespace std;
const int oo =1e18;
int m, n;
int a[505][505];
int dp[505][505];
main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>m>>n;
for (int i=1;i<=m;i++)
{
for (int j=1;j<=n;j++)
{
cin>>a[i][j];
}
}
for (int i=0;i<=m+1;i++)
{
for (int j=0;j<=n+1;j++)
{
dp[i][j]=oo;
}
}
for (int i=1;i<=m;i++)
{
dp[i][1] = a[i][1];
}
for (int j =2;j<=n;j++)
{
for (int i = 1;i<=m;i++)
{
int res = min({dp[i-1][j-1], dp[i][j-1], dp[i+1][j-1]});
dp[i][j] = res+ a[i][j];
}
}
int ans =oo;
for (int i =1;i<=m;i++)
{
ans =min(ans, dp[i][n]);
}
cout<<ans;
}
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