#include<bits/stdc++.h> using namespace std; typedef unsigned int uint; typedef long long int ll; typedef unsigned long long int ull; #define debugv(v) printf("L%d %s => ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl; #define debugm(m) printf("L%d %s is..\n",__LINE__,#m);for(auto v:m){for(auto e:v){cout<<e<<" ";}cout<<endl;} #define debuga(m,w) printf("L%d %s is => ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl; #define debugaa(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[x][y]<<" ";}cout<<endl;} #define debugaar(m,w,h) printf("L%d %s is..\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;} #define ALL(v) (v).begin(),(v).end() #define BIGINT 0x7FFFFFFF #define E107 1000000007 void printbit(int u){if(u==0)cout<<0;else{int s=0,k=0;for(;0<u;u>>=1,k++)s=(s<<1)|(u&1);for(;0<k--;s>>=1)cout<<(s&1);}} #define TIME chrono::system_clock::now() #define MILLISEC(t) (chrono::duration_cast<chrono::milliseconds>(t).count()) template<typename T1,typename T2> ostream& operator <<(ostream &o,const pair<T1,T2> p){o<<"("<<p.first<<":"<<p.second<<")";return o;} int width,height; int m,n; int main(){ int i,j,k; int x,y,a,b; cin >> height >> width; n = height*width; vector<valarray<int>> mat_s(n); valarray<int> vec_r(n); for (i=0;i<n;i++){ mat_s[i].resize(n); } for (i=0;i<n;i++){ cin >> vec_r [i]; } for (i=0;i<n;i++){ x=i%width; y=i/width; for (a=-1+(x==0);a<=1-(x==width-1);a++){ for (b=-1+(y==0);b<=1-(y==height-1);b++){ mat_s[i][x+a+(y+b)*width]=1; } } mat_s[x+y][i]; } //debugaar(mat_s,n,n) for (i=0;i<n;i++){// yoko // pivot if (mat_s[i][i]==0){ for (j=i+1;j<n;j++){ if (mat_s[j][i]==1){ mat_s[j].swap(mat_s[i]); //mat_r[j].swap(mat_r[i]); swap(vec_r[i],vec_r[j]); break; } } } for (j=0;j<n;j++){ // tate if (i==j) continue; if (mat_s[j][i]==0) continue; mat_s[j]^=mat_s[i]; vec_r[j]^=vec_r[i]; } } //debugaar(mat_s,n,n) //debugv(vec_r) int result=0; for (i=0;i<n;i++){ result+=(vec_r[i]); } cout << result << endl; return 0; }