problem

solution

codes

#include
    
     #include
     
      #include
      
       #define maxn 100001using namespace std;int a[maxn], b[maxn], c[maxn];int main(){    string s1, s2;    cin>>s1>>s2;    a[0]=s1.size(); b[0]=s2.size(); c[0]=a[0]+b[0]+1;    for(int i = 1; i <= a[0]; i++)a[i] = s1[a[0]-i]-'0';    for(int i = 1; i <= b[0]; i++)b[i] = s2[b[0]-i]-'0';    for(int i = 1; i <= a[0]; i++){        for(int j = 1; j <= b[0]; j++){            c[i+j-1] += a[i]*b[j];            if(c[i+j-1] >= 10){                c[i+j] += c[i+j-1]/10;                c[i+j-1] %= 10;            }        }    }    while(c[0]>1 && c[c[0]]==0)c[0]--;    for(int i = c[0]; i >= 1; i--)        cout<