#include<bits/stdc++.h> using namespace std; const int N = 1e3 + 10; int n , m; int k; double a[1010][1010]; double f[1010][1010]; signed main() { cin >> n >> m; cin >> k; for(int i = 1;i <= k;i++) { int x , y; cin >> x >> y; a[x][y] = 1; } for(int i = 1;i <= n;i++) f[i][0] = i * 100; for(int j = 1;j <= m;j++) f[0][j] = j * 100; for(int i = 1;i <= n;i++) { for(int j = 1;j <= m;j++) { if(a[i][j] == 0) f[i][j] = min(f[i - 1][j] + 100 , f[i][j - 1] + 100); else if(a[i][j] == 1) f[i][j] = min(min(f[i - 1][j] + 100 , f[i][j - 1] + 100) , f[i - 1][j - 1] + 141.421356237); } } cout << round(f[n][m]); return 0; }