#include<bits/stdc++.h>
using namespace std;
int k,n,m,v,w,a[501],b[501],c[501],f[501][501],p[501][501];
char s[501],t[501];
vector <pair<int,int>> ans,sub[2];
void dfs(int x,int y){
    if(!x&&!y) return;
    if(p[x][y]<2) sub[a[x+y]<=b[x]].push_back({b[x],a[x+y]}),dfs(x-1,y);
    else sub[a[x+y]<=c[y]].push_back({c[y],a[x+y]}),dfs(x,y-1);
}
int main(){
	scanf("%d%d%s%s",&k,&v,s+1,t+1);
    for(int i=1,j=0;i<=k;i++) if(s[i]=='2') a[++j]=i;
    for(int i=1;i<=k;i++) if(t[i]=='2') i&1?b[++n]=i:c[++m]=i;
    memset(f,0x3f,sizeof(f)),f[0][0]=0;
    for(int i=0;i<=n;i++){
        for(int j=0;j<=m;j++){
            if(i<n){
                w=f[i][j]+abs(a[i+j+1]-b[i+1])/2*(v+4)+abs(a[i+j+1]-b[i+1])%2*(v+3);
                for(int k=1;k<=j;k++) w+=c[k]>b[i+1];
                if(f[i+1][j]>w) f[i+1][j]=w,p[i+1][j]=1;
            }
            if(j<m){
                w=f[i][j]+abs(a[i+j+1]-c[j+1])/2*(v+4)+abs(a[i+j+1]-c[j+1])%2*(v+3);
                for(int k=1;k<=i;k++) w+=b[k]>c[j+1];
                if(f[i][j+1]>w) f[i][j+1]=w,p[i][j+1]=2;
            }
        }
    }
    dfs(n,m);
    for(int i:{0,1}) sort(begin(sub[i]),end(sub[i]));
    reverse(begin(sub[1]),end(sub[1]));
    for(auto [t,s]:sub[1]){
        while(t-s>=2) ans.push_back({s,s+2}),s+=2;
        if(s!=t) ans.push_back({s,t});
    }
    for(auto [t,s]:sub[0]){
        while(s-t>=2) ans.push_back({s-2,s}),s-=2;
        if(s!=t) ans.push_back({t,s});
    }
    printf("%d\n",ans.size());
    for(auto [l,r]:ans) printf("%d %d\n",l,r);
	return 0;
}